diff --git a/src/core/uritemplate/include/sourcemeta/core/uritemplate_router.h b/src/core/uritemplate/include/sourcemeta/core/uritemplate_router.h
index 5bc8c20e7..f140a2630 100644
--- a/src/core/uritemplate/include/sourcemeta/core/uritemplate_router.h
+++ b/src/core/uritemplate/include/sourcemeta/core/uritemplate_router.h
@@ -11,6 +11,7 @@
 #include <functional>  // std::function
 #include <memory>      // std::unique_ptr
 #include <span>        // std::span
+#include <string>      // std::string
 #include <string_view> // std::string_view
 #include <utility>     // std::pair
 #include <variant>     // std::variant
@@ -99,9 +100,12 @@ class SOURCEMETA_CORE_URITEMPLATE_EXPORT URITemplateRouter {
   [[nodiscard]] auto arguments() const noexcept
       -> const std::vector<std::pair<Identifier, std::vector<Argument>>> &;
 
+  /// Access the base path prefix
+  [[nodiscard]] auto base_path() const noexcept -> std::string_view;
+
 private:
   Node root_;
-  std::string_view base_path_;
+  std::string base_path_;
   std::vector<std::pair<Identifier, std::vector<Argument>>> arguments_;
 };
 
@@ -109,25 +113,6 @@ class SOURCEMETA_CORE_URITEMPLATE_EXPORT URITemplateRouter {
 /// A read-only view of a serialized URI Template router
 class SOURCEMETA_CORE_URITEMPLATE_EXPORT URITemplateRouterView {
 public:
-  /// A serialized node in the binary format
-#if defined(_MSC_VER)
-#pragma warning(push)
-#pragma warning(disable : 4324)
-#endif
-  struct alignas(8) Node {
-    std::uint32_t string_offset;
-    std::uint32_t string_length;
-    std::uint32_t first_literal_child;
-    std::uint32_t literal_child_count;
-    std::uint32_t variable_child;
-    URITemplateRouter::NodeType type;
-    std::uint8_t padding;
-    URITemplateRouter::Identifier identifier;
-  };
-#if defined(_MSC_VER)
-#pragma warning(pop)
-#endif
-
   /// Save a router to a binary file
   static auto save(const URITemplateRouter &router,
                    const std::filesystem::path &path) -> void;
@@ -153,6 +138,9 @@ class SOURCEMETA_CORE_URITEMPLATE_EXPORT URITemplateRouterView {
                  const URITemplateRouter::ArgumentCallback &callback) const
       -> void;
 
+  /// Access the base path prefix
+  [[nodiscard]] auto base_path() const noexcept -> std::string_view;
+
 private:
   std::vector<std::uint8_t> data_;
 };
diff --git a/src/core/uritemplate/uritemplate_router.cc b/src/core/uritemplate/uritemplate_router.cc
index c4b44d08c..4f6bfc965 100644
--- a/src/core/uritemplate/uritemplate_router.cc
+++ b/src/core/uritemplate/uritemplate_router.cc
@@ -97,6 +97,16 @@ inline auto extract_segment(const char *start, const char *end)
 URITemplateRouter::URITemplateRouter(const std::string_view base_path)
     : base_path_{base_path} {
   assert(this->base_path_.empty() || this->base_path_.front() == '/');
+  const auto last = this->base_path_.find_last_not_of('/');
+  if (last == std::string::npos) {
+    this->base_path_.clear();
+  } else {
+    this->base_path_.erase(last + 1);
+  }
+}
+
+auto URITemplateRouter::base_path() const noexcept -> std::string_view {
+  return this->base_path_;
 }
 
 auto URITemplateRouter::add(const std::string_view uri_template,
diff --git a/src/core/uritemplate/uritemplate_router_view.cc b/src/core/uritemplate/uritemplate_router_view.cc
index 2a2b876ac..c3481f24a 100644
--- a/src/core/uritemplate/uritemplate_router_view.cc
+++ b/src/core/uritemplate/uritemplate_router_view.cc
@@ -14,7 +14,7 @@ namespace sourcemeta::core {
 namespace {
 
 constexpr std::uint32_t ROUTER_MAGIC = 0x52544552; // "RTER"
-constexpr std::uint32_t ROUTER_VERSION = 2;
+constexpr std::uint32_t ROUTER_VERSION = 3;
 constexpr std::uint32_t NO_CHILD = std::numeric_limits<std::uint32_t>::max();
 
 // Type tags for argument value serialization
@@ -28,6 +28,8 @@ struct RouterHeader {
   std::uint32_t node_count;
   std::uint32_t string_table_offset;
   std::uint32_t arguments_offset;
+  std::uint32_t base_path_offset;
+  std::uint32_t base_path_length;
 };
 
 struct ArgumentEntryHeader {
@@ -36,9 +38,20 @@ struct ArgumentEntryHeader {
   std::uint32_t blob_length;
 };
 
+struct alignas(8) SerializedNode {
+  std::uint32_t string_offset;
+  std::uint32_t string_length;
+  std::uint32_t first_literal_child;
+  std::uint32_t literal_child_count;
+  std::uint32_t variable_child;
+  URITemplateRouter::NodeType type;
+  std::uint8_t padding;
+  URITemplateRouter::Identifier identifier;
+};
+
 // Binary search for a literal child matching the given segment
 inline auto binary_search_literal_children(
-    const URITemplateRouterView::Node *nodes, const char *string_table,
+    const SerializedNode *nodes, const char *string_table,
     const std::size_t string_table_size, const std::uint32_t first_child,
     const std::uint32_t child_count, const char *segment,
     const std::uint32_t segment_length) noexcept -> std::uint32_t {
@@ -82,7 +95,7 @@ inline auto binary_search_literal_children(
 
 auto URITemplateRouterView::save(const URITemplateRouter &router,
                                  const std::filesystem::path &path) -> void {
-  std::vector<Node> nodes;
+  std::vector<SerializedNode> nodes;
   std::string string_table;
   std::queue<const URITemplateRouter::Node *> queue;
   std::unordered_map<const URITemplateRouter::Node *, std::uint32_t>
@@ -90,7 +103,7 @@ auto URITemplateRouterView::save(const URITemplateRouter &router,
 
   const auto &root = router.root();
 
-  Node root_serialized{};
+  SerializedNode root_serialized{};
   root_serialized.string_offset = 0;
   root_serialized.string_length = 0;
   root_serialized.type = URITemplateRouter::NodeType::Root;
@@ -125,7 +138,7 @@ auto URITemplateRouterView::save(const URITemplateRouter &router,
     const auto *node = queue.front();
     queue.pop();
 
-    Node serialized{};
+    SerializedNode serialized{};
     serialized.string_offset = static_cast<std::uint32_t>(string_table.size());
     serialized.type = node->type;
     serialized.string_length = static_cast<std::uint32_t>(node->value.size());
@@ -224,14 +237,22 @@ auto URITemplateRouterView::save(const URITemplateRouter &router,
     argument_entries.push_back(entry);
   }
 
+  // Append the base path to the string table
+  const auto base_path_string_offset =
+      static_cast<std::uint32_t>(string_table.size());
+  const auto base_path_value = router.base_path();
+  string_table.append(base_path_value.data(), base_path_value.size());
+
   RouterHeader header{};
   header.magic = ROUTER_MAGIC;
   header.version = ROUTER_VERSION;
   header.node_count = static_cast<std::uint32_t>(nodes.size());
   header.string_table_offset = static_cast<std::uint32_t>(
-      sizeof(RouterHeader) + nodes.size() * sizeof(Node));
+      sizeof(RouterHeader) + nodes.size() * sizeof(SerializedNode));
   header.arguments_offset = static_cast<std::uint32_t>(
       header.string_table_offset + string_table.size());
+  header.base_path_offset = base_path_string_offset;
+  header.base_path_length = static_cast<std::uint32_t>(base_path_value.size());
 
   std::ofstream file(path, std::ios::binary);
   if (!file) {
@@ -239,8 +260,9 @@ auto URITemplateRouterView::save(const URITemplateRouter &router,
   }
 
   file.write(reinterpret_cast<const char *>(&header), sizeof(header));
-  file.write(reinterpret_cast<const char *>(nodes.data()),
-             static_cast<std::streamsize>(nodes.size() * sizeof(Node)));
+  file.write(
+      reinterpret_cast<const char *>(nodes.data()),
+      static_cast<std::streamsize>(nodes.size() * sizeof(SerializedNode)));
   file.write(string_table.data(),
              static_cast<std::streamsize>(string_table.size()));
 
@@ -306,15 +328,15 @@ auto URITemplateRouterView::match(const std::string_view path,
   }
 
   if (header->node_count == 0 ||
-      header->node_count >
-          (this->data_.size() - sizeof(RouterHeader)) / sizeof(Node)) {
+      header->node_count > (this->data_.size() - sizeof(RouterHeader)) /
+                               sizeof(SerializedNode)) {
     return 0;
   }
 
-  const auto *nodes =
-      reinterpret_cast<const Node *>(this->data_.data() + sizeof(RouterHeader));
+  const auto *nodes = reinterpret_cast<const SerializedNode *>(
+      this->data_.data() + sizeof(RouterHeader));
   const auto nodes_size =
-      static_cast<std::size_t>(header->node_count) * sizeof(Node);
+      static_cast<std::size_t>(header->node_count) * sizeof(SerializedNode);
   const auto expected_string_table_offset = sizeof(RouterHeader) + nodes_size;
   if (header->string_table_offset < expected_string_table_offset ||
       header->string_table_offset > this->data_.size()) {
@@ -599,4 +621,37 @@ auto URITemplateRouterView::arguments(
   }
 }
 
+auto URITemplateRouterView::base_path() const noexcept -> std::string_view {
+  if (this->data_.size() < sizeof(RouterHeader)) {
+    return {};
+  }
+
+  const auto *header =
+      reinterpret_cast<const RouterHeader *>(this->data_.data());
+  if (header->magic != ROUTER_MAGIC || header->version != ROUTER_VERSION) {
+    return {};
+  }
+
+  if (header->base_path_length == 0) {
+    return {};
+  }
+
+  if (header->string_table_offset > this->data_.size() ||
+      header->arguments_offset < header->string_table_offset ||
+      header->arguments_offset > this->data_.size()) {
+    return {};
+  }
+
+  const auto *string_table = reinterpret_cast<const char *>(
+      this->data_.data() + header->string_table_offset);
+  const auto string_table_size =
+      header->arguments_offset - header->string_table_offset;
+  if (header->base_path_offset > string_table_size ||
+      header->base_path_length > string_table_size - header->base_path_offset) {
+    return {};
+  }
+
+  return {string_table + header->base_path_offset, header->base_path_length};
+}
+
 } // namespace sourcemeta::core
diff --git a/test/uritemplate/uritemplate_router_test.cc b/test/uritemplate/uritemplate_router_test.cc
index 7d32c0f87..65046ad7a 100644
--- a/test/uritemplate/uritemplate_router_test.cc
+++ b/test/uritemplate/uritemplate_router_test.cc
@@ -25,6 +25,7 @@
 
 TEST(URITemplateRouter, single_literal_route) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   EXPECT_ROUTER_MATCH(router, "/users", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -32,6 +33,7 @@ TEST(URITemplateRouter, single_literal_route) {
 
 TEST(URITemplateRouter, single_literal_route_no_match) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   EXPECT_ROUTER_MATCH(router, "/posts", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -39,6 +41,7 @@ TEST(URITemplateRouter, single_literal_route_no_match) {
 
 TEST(URITemplateRouter, multi_segment_literal) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/list", 1);
   EXPECT_ROUTER_MATCH(router, "/users/list", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -46,6 +49,7 @@ TEST(URITemplateRouter, multi_segment_literal) {
 
 TEST(URITemplateRouter, single_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/{id}", 1);
   EXPECT_ROUTER_MATCH(router, "/users/123", 1, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -54,6 +58,7 @@ TEST(URITemplateRouter, single_variable) {
 
 TEST(URITemplateRouter, multiple_variables) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/{id}/posts/{post_id}", 1);
   EXPECT_ROUTER_MATCH(router, "/users/42/posts/99", 1, captures);
   EXPECT_EQ(captures.size(), 2);
@@ -63,6 +68,7 @@ TEST(URITemplateRouter, multiple_variables) {
 
 TEST(URITemplateRouter, literal_before_variable_precedence) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/me", 1);
   router.add("/users/{id}", 2);
   EXPECT_ROUTER_MATCH(router, "/users/me", 1, captures);
@@ -71,6 +77,7 @@ TEST(URITemplateRouter, literal_before_variable_precedence) {
 
 TEST(URITemplateRouter, variable_fallback) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/me", 1);
   router.add("/users/{id}", 2);
   EXPECT_ROUTER_MATCH(router, "/users/123", 2, captures);
@@ -80,6 +87,7 @@ TEST(URITemplateRouter, variable_fallback) {
 
 TEST(URITemplateRouter, multiple_routes_match_users) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   router.add("/users/{id}", 2);
   router.add("/posts", 3);
@@ -90,6 +98,7 @@ TEST(URITemplateRouter, multiple_routes_match_users) {
 
 TEST(URITemplateRouter, multiple_routes_match_users_id) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   router.add("/users/{id}", 2);
   router.add("/posts", 3);
@@ -101,6 +110,7 @@ TEST(URITemplateRouter, multiple_routes_match_users_id) {
 
 TEST(URITemplateRouter, multiple_routes_match_posts) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   router.add("/users/{id}", 2);
   router.add("/posts", 3);
@@ -111,6 +121,7 @@ TEST(URITemplateRouter, multiple_routes_match_posts) {
 
 TEST(URITemplateRouter, multiple_routes_match_posts_id) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   router.add("/users/{id}", 2);
   router.add("/posts", 3);
@@ -122,24 +133,28 @@ TEST(URITemplateRouter, multiple_routes_match_posts_id) {
 
 TEST(URITemplateRouter, no_match_partial_path) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/{id}/posts", 1);
   EXPECT_ROUTER_MATCH(router, "/users/123", 0, captures);
 }
 
 TEST(URITemplateRouter, no_match_extra_segments) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   EXPECT_ROUTER_MATCH(router, "/users/123", 0, captures);
 }
 
 TEST(URITemplateRouter, empty_path) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   EXPECT_ROUTER_MATCH(router, "", 0, captures);
 }
 
 TEST(URITemplateRouter, root_template_matches_root) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/", 1);
   EXPECT_ROUTER_MATCH(router, "/", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -147,6 +162,7 @@ TEST(URITemplateRouter, root_template_matches_root) {
 
 TEST(URITemplateRouter, root_template_no_match_empty) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/", 1);
   EXPECT_ROUTER_MATCH(router, "", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -154,6 +170,7 @@ TEST(URITemplateRouter, root_template_no_match_empty) {
 
 TEST(URITemplateRouter, root_template_no_match_path) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/", 1);
   EXPECT_ROUTER_MATCH(router, "/foo", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -161,6 +178,7 @@ TEST(URITemplateRouter, root_template_no_match_path) {
 
 TEST(URITemplateRouter, empty_template_matches_empty) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   EXPECT_ROUTER_MATCH(router, "", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -168,6 +186,7 @@ TEST(URITemplateRouter, empty_template_matches_empty) {
 
 TEST(URITemplateRouter, empty_template_no_match_root) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   EXPECT_ROUTER_MATCH(router, "/", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -175,6 +194,7 @@ TEST(URITemplateRouter, empty_template_no_match_root) {
 
 TEST(URITemplateRouter, empty_template_no_match_path) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   EXPECT_ROUTER_MATCH(router, "/foo", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -182,6 +202,7 @@ TEST(URITemplateRouter, empty_template_no_match_path) {
 
 TEST(URITemplateRouter, root_and_other_routes_match_root) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/", 1);
   router.add("/users", 2);
   router.add("/users/{id}", 3);
@@ -191,6 +212,7 @@ TEST(URITemplateRouter, root_and_other_routes_match_root) {
 
 TEST(URITemplateRouter, root_and_other_routes_match_users) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/", 1);
   router.add("/users", 2);
   router.add("/users/{id}", 3);
@@ -200,6 +222,7 @@ TEST(URITemplateRouter, root_and_other_routes_match_users) {
 
 TEST(URITemplateRouter, root_and_other_routes_match_users_id) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/", 1);
   router.add("/users", 2);
   router.add("/users/{id}", 3);
@@ -210,6 +233,7 @@ TEST(URITemplateRouter, root_and_other_routes_match_users_id) {
 
 TEST(URITemplateRouter, empty_and_root_together_match_empty) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   router.add("/", 2);
   EXPECT_ROUTER_MATCH(router, "", 1, captures);
@@ -218,6 +242,7 @@ TEST(URITemplateRouter, empty_and_root_together_match_empty) {
 
 TEST(URITemplateRouter, empty_and_root_together_match_root) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   router.add("/", 2);
   EXPECT_ROUTER_MATCH(router, "/", 2, captures);
@@ -226,6 +251,7 @@ TEST(URITemplateRouter, empty_and_root_together_match_root) {
 
 TEST(URITemplateRouter, empty_and_root_together_no_match_path) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   router.add("/", 2);
   EXPECT_ROUTER_MATCH(router, "/foo", 0, captures);
@@ -234,6 +260,7 @@ TEST(URITemplateRouter, empty_and_root_together_no_match_path) {
 
 TEST(URITemplateRouter, empty_and_root_and_others_match_empty) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   router.add("/", 2);
   router.add("/users", 3);
@@ -244,6 +271,7 @@ TEST(URITemplateRouter, empty_and_root_and_others_match_empty) {
 
 TEST(URITemplateRouter, empty_and_root_and_others_match_root) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   router.add("/", 2);
   router.add("/users", 3);
@@ -254,6 +282,7 @@ TEST(URITemplateRouter, empty_and_root_and_others_match_root) {
 
 TEST(URITemplateRouter, empty_and_root_and_others_match_users) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   router.add("/", 2);
   router.add("/users", 3);
@@ -264,6 +293,7 @@ TEST(URITemplateRouter, empty_and_root_and_others_match_users) {
 
 TEST(URITemplateRouter, empty_and_root_and_others_match_users_id) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("", 1);
   router.add("/", 2);
   router.add("/users", 3);
@@ -275,6 +305,7 @@ TEST(URITemplateRouter, empty_and_root_and_others_match_users_id) {
 
 TEST(URITemplateRouter, binary_search_literals_gamma) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/alpha", 1);
   router.add("/beta", 2);
   router.add("/gamma", 3);
@@ -286,6 +317,7 @@ TEST(URITemplateRouter, binary_search_literals_gamma) {
 
 TEST(URITemplateRouter, binary_search_literals_alpha) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/alpha", 1);
   router.add("/beta", 2);
   router.add("/gamma", 3);
@@ -297,6 +329,7 @@ TEST(URITemplateRouter, binary_search_literals_alpha) {
 
 TEST(URITemplateRouter, binary_search_literals_epsilon) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/alpha", 1);
   router.add("/beta", 2);
   router.add("/gamma", 3);
@@ -308,6 +341,7 @@ TEST(URITemplateRouter, binary_search_literals_epsilon) {
 
 TEST(URITemplateRouter, conflicting_variable_names_throws) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/{user_id}/posts", 1);
   try {
     router.add("/users/{id}/comments", 2);
@@ -322,6 +356,7 @@ TEST(URITemplateRouter, conflicting_variable_names_throws) {
 
 TEST(URITemplateRouter, same_variable_names_allowed) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/{id}/posts", 1);
   router.add("/users/{id}/comments", 2);
   EXPECT_ROUTER_MATCH(router, "/users/123/posts", 1, captures);
@@ -331,6 +366,7 @@ TEST(URITemplateRouter, same_variable_names_allowed) {
 
 TEST(URITemplateRouter, conflicting_expansion_variable_names_throws) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{id}", 1);
   try {
     router.add("/files/{+path}", 2);
@@ -345,6 +381,7 @@ TEST(URITemplateRouter, conflicting_expansion_variable_names_throws) {
 
 TEST(URITemplateRouter, reserved_expansion_catch_all) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{+path}", 1);
   EXPECT_ROUTER_MATCH(router, "/files/foo/bar/baz.txt", 1, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -353,6 +390,7 @@ TEST(URITemplateRouter, reserved_expansion_catch_all) {
 
 TEST(URITemplateRouter, reserved_expansion_single_segment) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{+path}", 1);
   EXPECT_ROUTER_MATCH(router, "/files/readme.md", 1, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -361,6 +399,7 @@ TEST(URITemplateRouter, reserved_expansion_single_segment) {
 
 TEST(URITemplateRouter, reserved_expansion_with_literal_prefix) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/api/v1/proxy/{+url}", 1);
   EXPECT_ROUTER_MATCH(router, "/api/v1/proxy/https://example.com/path", 1,
                       captures);
@@ -370,6 +409,7 @@ TEST(URITemplateRouter, reserved_expansion_with_literal_prefix) {
 
 TEST(URITemplateRouter, reserved_expansion_matches_single_segment) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{+path}", 1);
   EXPECT_ROUTER_MATCH(router, "/files/123", 1, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -378,6 +418,7 @@ TEST(URITemplateRouter, reserved_expansion_matches_single_segment) {
 
 TEST(URITemplateRouter, reserved_expansion_matches_multi_segment) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{+path}", 1);
   EXPECT_ROUTER_MATCH(router, "/files/foo/bar", 1, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -386,6 +427,7 @@ TEST(URITemplateRouter, reserved_expansion_matches_multi_segment) {
 
 TEST(URITemplateRouter, expansion_takes_priority_over_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{path}", 1);
   router.add("/files/{+path}", 2);
   EXPECT_ROUTER_MATCH(router, "/files/readme.md", 2, captures);
@@ -395,6 +437,7 @@ TEST(URITemplateRouter, expansion_takes_priority_over_variable) {
 
 TEST(URITemplateRouter, expansion_takes_priority_multi_segment) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{path}", 1);
   router.add("/files/{+path}", 2);
   EXPECT_ROUTER_MATCH(router, "/files/foo/bar/baz", 2, captures);
@@ -404,6 +447,7 @@ TEST(URITemplateRouter, expansion_takes_priority_multi_segment) {
 
 TEST(URITemplateRouter, expansion_first_then_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{+path}", 1);
   router.add("/files/{path}", 2);
   EXPECT_ROUTER_MATCH(router, "/files/readme.md", 1, captures);
@@ -413,6 +457,7 @@ TEST(URITemplateRouter, expansion_first_then_variable) {
 
 TEST(URITemplateRouter, literal_takes_priority_over_expansion) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{+path}", 1);
   router.add("/files/special", 2);
   EXPECT_ROUTER_MATCH(router, "/files/special", 2, captures);
@@ -421,6 +466,7 @@ TEST(URITemplateRouter, literal_takes_priority_over_expansion) {
 
 TEST(URITemplateRouter, expansion_fallback_from_literal) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{+path}", 1);
   router.add("/files/special", 2);
   EXPECT_ROUTER_MATCH(router, "/files/other", 1, captures);
@@ -430,192 +476,230 @@ TEST(URITemplateRouter, expansion_fallback_from_literal) {
 
 TEST(URITemplateRouter, literal_suffix_after_variable_throws) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar}.json", 1, "{bar}.json");
 }
 
 TEST(URITemplateRouter, literal_prefix_before_variable_throws) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/prefix{bar}", 1, "prefix{bar}");
 }
 
 TEST(URITemplateRouter, mixed_segment_variable_then_literal_suffix) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/{id}.html", 1, "{id}.html");
 }
 
 TEST(URITemplateRouter, mixed_segment_expansion_then_literal_suffix) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/files/{+path}.bak", 1, "{+path}.bak");
 }
 
 TEST(URITemplateRouter, mixed_segment_prefix_before_expansion_throws) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/api/v1{+rest}", 1, "v1{+rest}");
 }
 
 TEST(URITemplateRouter, mixed_segment_suffix_in_middle) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar}.json/baz", 1, "{bar}.json");
 }
 
 TEST(URITemplateRouter, mixed_segment_prefix_in_middle) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/prefix{bar}/baz", 1, "prefix{bar}");
 }
 
 TEST(URITemplateRouter, mixed_segment_expansion_suffix_in_middle) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/files/{+path}.txt/meta", 1,
                               "{+path}.txt");
 }
 
 TEST(URITemplateRouter, mixed_segment_expansion_prefix_in_middle) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/api/v2{+path}/end", 1, "v2{+path}");
 }
 
 TEST(URITemplateRouter, error_unclosed_brace) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar", 1, "{bar");
 }
 
 TEST(URITemplateRouter, error_unclosed_brace_at_end) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/bar{", 1, "bar{");
 }
 
 TEST(URITemplateRouter, error_empty_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{}", 1, "{}");
 }
 
 TEST(URITemplateRouter, error_empty_expansion) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{+}", 1, "{+}");
 }
 
 TEST(URITemplateRouter, error_nested_brace) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{{bar}}", 1, "{{bar}}");
 }
 
 TEST(URITemplateRouter, error_unmatched_close_brace) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/bar}", 1, "bar}");
 }
 
 TEST(URITemplateRouter, error_space_before_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{ bar}", 1, "{ bar}");
 }
 
 TEST(URITemplateRouter, error_space_after_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar }", 1, "{bar }");
 }
 
 TEST(URITemplateRouter, error_space_in_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar baz}", 1, "{bar baz}");
 }
 
 TEST(URITemplateRouter, error_invalid_variable_start) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{-bar}", 1, "{-bar}");
 }
 
 TEST(URITemplateRouter, error_invalid_character_in_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar!baz}", 1, "{bar!baz}");
 }
 
 TEST(URITemplateRouter, error_reserved_operator_equals) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{=bar}", 1, "{=bar}");
 }
 
 TEST(URITemplateRouter, error_reserved_operator_pipe) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{|bar}", 1, "{|bar}");
 }
 
 TEST(URITemplateRouter, error_reserved_operator_exclamation) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{!bar}", 1, "{!bar}");
 }
 
 TEST(URITemplateRouter, error_reserved_operator_at) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{@bar}", 1, "{@bar}");
 }
 
 TEST(URITemplateRouter, error_bracket_in_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar[0]}", 1, "{bar[0]}");
 }
 
 TEST(URITemplateRouter, error_multiple_variables) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar,baz}", 1, "{bar,baz}");
 }
 
 TEST(URITemplateRouter, error_prefix_modifier) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar:3}", 1, "{bar:3}");
 }
 
 TEST(URITemplateRouter, error_explode_modifier) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{bar*}", 1, "{bar*}");
 }
 
 TEST(URITemplateRouter, error_unsupported_fragment_expansion) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{#bar}", 1, "{#bar}");
 }
 
 TEST(URITemplateRouter, error_unsupported_label_expansion) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{.bar}", 1, "{.bar}");
 }
 
 TEST(URITemplateRouter, error_unsupported_path_expansion) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{/bar}", 1, "{/bar}");
 }
 
 TEST(URITemplateRouter, error_unsupported_path_parameter_expansion) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{;bar}", 1, "{;bar}");
 }
 
 TEST(URITemplateRouter, error_unsupported_query_expansion) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{?bar}", 1, "{?bar}");
 }
 
 TEST(URITemplateRouter, error_unsupported_query_continuation_expansion) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{&bar}", 1, "{&bar}");
 }
 
 TEST(URITemplateRouter, error_expansion_not_last_segment_literal) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{+bar}/baz", 1, "{+bar}");
 }
 
 TEST(URITemplateRouter, error_expansion_not_last_segment_variable) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{+bar}/{baz}", 1, "{+bar}");
 }
 
 TEST(URITemplateRouter, error_expansion_not_last_segment_trailing_slash) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   EXPECT_ROUTER_SEGMENT_ERROR(router, "/foo/{+bar}/", 1, "{+bar}");
 }
 
 TEST(URITemplateRouter, trailing_slash_no_match) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   EXPECT_ROUTER_MATCH(router, "/users/", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -623,6 +707,7 @@ TEST(URITemplateRouter, trailing_slash_no_match) {
 
 TEST(URITemplateRouter, multiple_trailing_slashes_no_match) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   EXPECT_ROUTER_MATCH(router, "/users///", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -630,6 +715,7 @@ TEST(URITemplateRouter, multiple_trailing_slashes_no_match) {
 
 TEST(URITemplateRouter, leading_double_slash_no_match) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users", 1);
   EXPECT_ROUTER_MATCH(router, "//users", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -637,6 +723,7 @@ TEST(URITemplateRouter, leading_double_slash_no_match) {
 
 TEST(URITemplateRouter, internal_double_slashes_no_match) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/posts", 1);
   EXPECT_ROUTER_MATCH(router, "/users//posts", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -644,6 +731,7 @@ TEST(URITemplateRouter, internal_double_slashes_no_match) {
 
 TEST(URITemplateRouter, trailing_slash_with_variable_no_match) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/{id}", 1);
   EXPECT_ROUTER_MATCH(router, "/users/123/", 0, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -652,6 +740,7 @@ TEST(URITemplateRouter, trailing_slash_with_variable_no_match) {
 
 TEST(URITemplateRouter, internal_double_slash_with_variable_no_match) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/users/{id}/posts", 1);
   EXPECT_ROUTER_MATCH(router, "/users//123//posts", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -659,6 +748,7 @@ TEST(URITemplateRouter, internal_double_slash_with_variable_no_match) {
 
 TEST(URITemplateRouter, expansion_matches_trailing_slash) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{+path}", 1);
   EXPECT_ROUTER_MATCH(router, "/files/foo/bar/", 1, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -667,6 +757,7 @@ TEST(URITemplateRouter, expansion_matches_trailing_slash) {
 
 TEST(URITemplateRouter, expansion_matches_double_slashes) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/files/{+path}", 1);
   EXPECT_ROUTER_MATCH(router, "/files/foo//bar", 1, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -675,6 +766,7 @@ TEST(URITemplateRouter, expansion_matches_double_slashes) {
 
 TEST(URITemplateRouter, add_with_single_string_argument) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"responseSchema", std::string_view{"some/path"}}}};
   router.add("/test", 1, arguments);
@@ -694,6 +786,7 @@ TEST(URITemplateRouter, add_with_single_string_argument) {
 
 TEST(URITemplateRouter, add_with_single_integer_argument) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"maxItems", std::int64_t{42}}}};
   router.add("/test", 1, arguments);
@@ -713,6 +806,7 @@ TEST(URITemplateRouter, add_with_single_integer_argument) {
 
 TEST(URITemplateRouter, add_with_single_boolean_argument_true) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"verbose", true}}};
   router.add("/test", 1, arguments);
@@ -732,6 +826,7 @@ TEST(URITemplateRouter, add_with_single_boolean_argument_true) {
 
 TEST(URITemplateRouter, add_with_single_boolean_argument_false) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"verbose", false}}};
   router.add("/test", 1, arguments);
@@ -751,6 +846,7 @@ TEST(URITemplateRouter, add_with_single_boolean_argument_false) {
 
 TEST(URITemplateRouter, add_with_multiple_arguments) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 3> arguments{
       {{"responseSchema", std::string_view{"some/path"}},
        {"maxItems", std::int64_t{100}},
@@ -776,6 +872,7 @@ TEST(URITemplateRouter, add_with_multiple_arguments) {
 
 TEST(URITemplateRouter, add_with_empty_arguments_span) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/test", 1,
              std::span<const sourcemeta::core::URITemplateRouter::Argument>{});
   std::vector<std::pair<std::string_view,
@@ -791,6 +888,7 @@ TEST(URITemplateRouter, add_with_empty_arguments_span) {
 
 TEST(URITemplateRouter, add_without_arguments_parameter) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/test", 1);
   std::vector<std::pair<std::string_view,
                         sourcemeta::core::URITemplateRouter::ArgumentValue>>
@@ -805,6 +903,7 @@ TEST(URITemplateRouter, add_without_arguments_parameter) {
 
 TEST(URITemplateRouter, add_multiple_routes_with_arguments) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1>
       arguments_one{{{"schema", std::string_view{"path/one"}}}};
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1>
@@ -855,6 +954,7 @@ TEST(URITemplateRouter, add_multiple_routes_with_arguments) {
 
 TEST(URITemplateRouter, add_arguments_negative_integer) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"offset", std::int64_t{INT64_MIN}}}};
   router.add("/test", 1, arguments);
@@ -874,6 +974,7 @@ TEST(URITemplateRouter, add_arguments_negative_integer) {
 
 TEST(URITemplateRouter, add_arguments_zero_integer) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"count", std::int64_t{0}}}};
   router.add("/test", 1, arguments);
@@ -893,6 +994,7 @@ TEST(URITemplateRouter, add_arguments_zero_integer) {
 
 TEST(URITemplateRouter, add_arguments_max_integer) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"limit", std::int64_t{INT64_MAX}}}};
   router.add("/test", 1, arguments);
@@ -912,6 +1014,7 @@ TEST(URITemplateRouter, add_arguments_max_integer) {
 
 TEST(URITemplateRouter, add_arguments_empty_string_value) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"description", std::string_view{""}}}};
   router.add("/test", 1, arguments);
@@ -931,6 +1034,7 @@ TEST(URITemplateRouter, add_arguments_empty_string_value) {
 
 TEST(URITemplateRouter, add_arguments_empty_string_name) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"", std::string_view{"some_value"}}}};
   router.add("/test", 1, arguments);
@@ -950,6 +1054,7 @@ TEST(URITemplateRouter, add_arguments_empty_string_name) {
 
 TEST(URITemplateRouter, match_still_works_with_arguments) {
   sourcemeta::core::URITemplateRouter router;
+  EXPECT_TRUE(router.base_path().empty());
   const std::array<sourcemeta::core::URITemplateRouter::Argument, 1> arguments{
       {{"responseSchema", std::string_view{"schemas/user"}}}};
   router.add("/users/{id}", 1, arguments);
@@ -960,6 +1065,7 @@ TEST(URITemplateRouter, match_still_works_with_arguments) {
 
 TEST(URITemplateRouter, base_path_single_segment) {
   sourcemeta::core::URITemplateRouter router{"/prefix"};
+  EXPECT_EQ(router.base_path(), "/prefix");
   router.add("/foo", 1);
   EXPECT_ROUTER_MATCH(router, "/prefix/foo", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -967,6 +1073,7 @@ TEST(URITemplateRouter, base_path_single_segment) {
 
 TEST(URITemplateRouter, base_path_without_prefix_no_match) {
   sourcemeta::core::URITemplateRouter router{"/prefix"};
+  EXPECT_EQ(router.base_path(), "/prefix");
   router.add("/foo", 1);
   EXPECT_ROUTER_MATCH(router, "/foo", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -974,6 +1081,7 @@ TEST(URITemplateRouter, base_path_without_prefix_no_match) {
 
 TEST(URITemplateRouter, base_path_multi_segment) {
   sourcemeta::core::URITemplateRouter router{"/v1/catalog"};
+  EXPECT_EQ(router.base_path(), "/v1/catalog");
   router.add("/api/list", 1);
   router.add("/{+path}", 2);
   EXPECT_ROUTER_MATCH(router, "/v1/catalog/api/list", 1, captures_list);
@@ -985,6 +1093,7 @@ TEST(URITemplateRouter, base_path_multi_segment) {
 
 TEST(URITemplateRouter, base_path_with_variable) {
   sourcemeta::core::URITemplateRouter router{"/prefix"};
+  EXPECT_EQ(router.base_path(), "/prefix");
   router.add("/users/{id}", 1);
   EXPECT_ROUTER_MATCH(router, "/prefix/users/42", 1, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -993,6 +1102,7 @@ TEST(URITemplateRouter, base_path_with_variable) {
 
 TEST(URITemplateRouter, base_path_prefix_boundary_no_match) {
   sourcemeta::core::URITemplateRouter router{"/prefix"};
+  EXPECT_EQ(router.base_path(), "/prefix");
   router.add("/foo", 1);
   EXPECT_ROUTER_MATCH(router, "/prefixfoo", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -1000,6 +1110,7 @@ TEST(URITemplateRouter, base_path_prefix_boundary_no_match) {
 
 TEST(URITemplateRouter, base_path_with_empty_template) {
   sourcemeta::core::URITemplateRouter router{"/v1/catalog"};
+  EXPECT_EQ(router.base_path(), "/v1/catalog");
   router.add("", 1);
   EXPECT_ROUTER_MATCH(router, "/v1/catalog", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -1007,6 +1118,7 @@ TEST(URITemplateRouter, base_path_with_empty_template) {
 
 TEST(URITemplateRouter, base_path_slash_only_is_no_base_path) {
   sourcemeta::core::URITemplateRouter router{"/"};
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/foo", 1);
   EXPECT_ROUTER_MATCH(router, "/foo", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -1014,6 +1126,7 @@ TEST(URITemplateRouter, base_path_slash_only_is_no_base_path) {
 
 TEST(URITemplateRouter, base_path_trailing_slash_normalized) {
   sourcemeta::core::URITemplateRouter router{"/prefix/"};
+  EXPECT_EQ(router.base_path(), "/prefix");
   router.add("/foo", 1);
   EXPECT_ROUTER_MATCH(router, "/prefix/foo", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -1021,6 +1134,7 @@ TEST(URITemplateRouter, base_path_trailing_slash_normalized) {
 
 TEST(URITemplateRouter, base_path_multiple_trailing_slashes_normalized) {
   sourcemeta::core::URITemplateRouter router{"/prefix///"};
+  EXPECT_EQ(router.base_path(), "/prefix");
   router.add("/foo", 1);
   EXPECT_ROUTER_MATCH(router, "/prefix/foo", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -1028,6 +1142,7 @@ TEST(URITemplateRouter, base_path_multiple_trailing_slashes_normalized) {
 
 TEST(URITemplateRouter, base_path_expansion) {
   sourcemeta::core::URITemplateRouter router{"/api"};
+  EXPECT_EQ(router.base_path(), "/api");
   router.add("/files/{+path}", 1);
   EXPECT_ROUTER_MATCH(router, "/api/files/a/b/c", 1, captures);
   EXPECT_EQ(captures.size(), 1);
@@ -1036,12 +1151,14 @@ TEST(URITemplateRouter, base_path_expansion) {
 
 TEST(URITemplateRouter, base_path_trailing_slash_on_request_no_match) {
   sourcemeta::core::URITemplateRouter router{"/v1/catalog"};
+  EXPECT_EQ(router.base_path(), "/v1/catalog");
   router.add("/foo", 1);
   EXPECT_ROUTER_MATCH(router, "/v1/catalog/foo/", 0, captures);
 }
 
 TEST(URITemplateRouter, base_path_empty_string_is_no_base_path) {
   sourcemeta::core::URITemplateRouter router{""};
+  EXPECT_TRUE(router.base_path().empty());
   router.add("/foo", 1);
   EXPECT_ROUTER_MATCH(router, "/foo", 1, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -1049,6 +1166,7 @@ TEST(URITemplateRouter, base_path_empty_string_is_no_base_path) {
 
 TEST(URITemplateRouter, base_path_wrong_prefix_no_match) {
   sourcemeta::core::URITemplateRouter router{"/v1/catalog"};
+  EXPECT_EQ(router.base_path(), "/v1/catalog");
   router.add("/api/list", 1);
   EXPECT_ROUTER_MATCH(router, "/v2/catalog/api/list", 0, captures);
   EXPECT_EQ(captures.size(), 0);
@@ -1056,6 +1174,7 @@ TEST(URITemplateRouter, base_path_wrong_prefix_no_match) {
 
 TEST(URITemplateRouter, base_path_partial_prefix_no_match) {
   sourcemeta::core::URITemplateRouter router{"/v1/catalog"};
+  EXPECT_EQ(router.base_path(), "/v1/catalog");
   router.add("/api/list", 1);
   EXPECT_ROUTER_MATCH(router, "/v1/api/list", 0, captures);
   EXPECT_EQ(captures.size(), 0);
diff --git a/test/uritemplate/uritemplate_router_view_test.cc b/test/uritemplate/uritemplate_router_view_test.cc
index be4288b45..2de42497d 100644
--- a/test/uritemplate/uritemplate_router_view_test.cc
+++ b/test/uritemplate/uritemplate_router_view_test.cc
@@ -33,6 +33,7 @@ TEST_F(URITemplateRouterViewTest, single_literal_route) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -45,6 +46,7 @@ TEST_F(URITemplateRouterViewTest, single_literal_route_no_match) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/posts", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -57,6 +59,7 @@ TEST_F(URITemplateRouterViewTest, multi_segment_literal) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/list", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -69,6 +72,7 @@ TEST_F(URITemplateRouterViewTest, single_variable) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/123", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "123");
@@ -82,6 +86,7 @@ TEST_F(URITemplateRouterViewTest, multiple_variables) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/42/posts/99", 1, captures);
   EXPECT_EQ(captures.size(), 2);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "42");
@@ -97,6 +102,7 @@ TEST_F(URITemplateRouterViewTest, literal_before_variable_precedence) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/me", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -110,6 +116,7 @@ TEST_F(URITemplateRouterViewTest, variable_fallback) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/123", 2, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "123");
@@ -126,6 +133,7 @@ TEST_F(URITemplateRouterViewTest, multiple_routes_match_users) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -141,6 +149,7 @@ TEST_F(URITemplateRouterViewTest, multiple_routes_match_users_id) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/42", 2, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "42");
@@ -157,6 +166,7 @@ TEST_F(URITemplateRouterViewTest, multiple_routes_match_posts) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/posts", 3, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -172,6 +182,7 @@ TEST_F(URITemplateRouterViewTest, multiple_routes_match_posts_id) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/posts/99", 4, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "99");
@@ -189,6 +200,7 @@ TEST_F(URITemplateRouterViewTest, binary_search_literals_gamma) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/gamma", 3, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -205,6 +217,7 @@ TEST_F(URITemplateRouterViewTest, binary_search_literals_alpha) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/alpha", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -221,6 +234,7 @@ TEST_F(URITemplateRouterViewTest, binary_search_literals_epsilon) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/epsilon", 5, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -233,6 +247,7 @@ TEST_F(URITemplateRouterViewTest, root_template_matches_root) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -245,6 +260,7 @@ TEST_F(URITemplateRouterViewTest, root_template_no_match_empty) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -257,6 +273,7 @@ TEST_F(URITemplateRouterViewTest, root_template_no_match_path) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/foo", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -269,6 +286,7 @@ TEST_F(URITemplateRouterViewTest, empty_template_matches_empty) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -281,6 +299,7 @@ TEST_F(URITemplateRouterViewTest, empty_template_no_match_root) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -293,6 +312,7 @@ TEST_F(URITemplateRouterViewTest, empty_template_no_match_path) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/foo", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -307,6 +327,7 @@ TEST_F(URITemplateRouterViewTest, root_and_other_routes_match_root) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -321,6 +342,7 @@ TEST_F(URITemplateRouterViewTest, root_and_other_routes_match_users) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users", 2, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -335,6 +357,7 @@ TEST_F(URITemplateRouterViewTest, root_and_other_routes_match_users_id) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/123", 3, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "123");
@@ -349,6 +372,7 @@ TEST_F(URITemplateRouterViewTest, empty_and_root_together_match_empty) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -362,6 +386,7 @@ TEST_F(URITemplateRouterViewTest, empty_and_root_together_match_root) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/", 2, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -375,6 +400,7 @@ TEST_F(URITemplateRouterViewTest, empty_and_root_together_no_match_path) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/foo", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -390,6 +416,7 @@ TEST_F(URITemplateRouterViewTest, empty_and_root_and_others_match_empty) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -405,6 +432,7 @@ TEST_F(URITemplateRouterViewTest, empty_and_root_and_others_match_root) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/", 2, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -420,6 +448,7 @@ TEST_F(URITemplateRouterViewTest, empty_and_root_and_others_match_users) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users", 3, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -435,6 +464,7 @@ TEST_F(URITemplateRouterViewTest, empty_and_root_and_others_match_users_id) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/42", 4, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "42");
@@ -449,6 +479,7 @@ TEST_F(URITemplateRouterViewTest, same_variable_names_allowed) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/123/comments", 2, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "123");
@@ -462,6 +493,7 @@ TEST_F(URITemplateRouterViewTest, reserved_expansion_catch_all) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/foo/bar/baz.txt", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "foo/bar/baz.txt");
@@ -475,6 +507,7 @@ TEST_F(URITemplateRouterViewTest, reserved_expansion_with_literal_prefix) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/api/v1/proxy/https://example.com/path", 1,
                       captures);
   EXPECT_EQ(captures.size(), 1);
@@ -489,6 +522,7 @@ TEST_F(URITemplateRouterViewTest, reserved_expansion_matches_multi_segment) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/foo/bar", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "foo/bar");
@@ -503,6 +537,7 @@ TEST_F(URITemplateRouterViewTest, expansion_takes_priority_over_variable) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/readme.md", 2, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "readme.md");
@@ -517,6 +552,7 @@ TEST_F(URITemplateRouterViewTest, expansion_takes_priority_multi_segment) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/foo/bar/baz", 2, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "foo/bar/baz");
@@ -531,6 +567,7 @@ TEST_F(URITemplateRouterViewTest, expansion_first_then_variable) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/readme.md", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "readme.md");
@@ -545,6 +582,7 @@ TEST_F(URITemplateRouterViewTest, literal_takes_priority_over_expansion) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/special", 2, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -558,6 +596,7 @@ TEST_F(URITemplateRouterViewTest, expansion_fallback_from_literal) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/other", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "other");
@@ -571,6 +610,7 @@ TEST_F(URITemplateRouterViewTest, trailing_slash_no_match) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -583,6 +623,7 @@ TEST_F(URITemplateRouterViewTest, multiple_trailing_slashes_no_match) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users///", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -595,6 +636,7 @@ TEST_F(URITemplateRouterViewTest, leading_double_slash_no_match) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "//users", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -607,6 +649,7 @@ TEST_F(URITemplateRouterViewTest, internal_double_slashes_no_match) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users//posts", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -619,6 +662,7 @@ TEST_F(URITemplateRouterViewTest, trailing_slash_with_variable_no_match) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/123/", 0, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "123");
@@ -633,6 +677,7 @@ TEST_F(URITemplateRouterViewTest,
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users//123//posts", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -645,6 +690,7 @@ TEST_F(URITemplateRouterViewTest, expansion_matches_trailing_slash) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/foo/bar/", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "foo/bar/");
@@ -658,6 +704,7 @@ TEST_F(URITemplateRouterViewTest, expansion_matches_double_slashes) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/foo//bar", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "foo//bar");
@@ -915,6 +962,7 @@ TEST_F(URITemplateRouterViewTest, arguments_single_string) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -945,6 +993,7 @@ TEST_F(URITemplateRouterViewTest, arguments_single_integer) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -974,6 +1023,7 @@ TEST_F(URITemplateRouterViewTest, arguments_single_boolean_true) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1002,6 +1052,7 @@ TEST_F(URITemplateRouterViewTest, arguments_single_boolean_false) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1030,6 +1081,7 @@ TEST_F(URITemplateRouterViewTest, arguments_integer_zero) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1059,6 +1111,7 @@ TEST_F(URITemplateRouterViewTest, arguments_integer_negative) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1088,6 +1141,7 @@ TEST_F(URITemplateRouterViewTest, arguments_integer_min) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1117,6 +1171,7 @@ TEST_F(URITemplateRouterViewTest, arguments_integer_max) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1147,6 +1202,7 @@ TEST_F(URITemplateRouterViewTest, arguments_empty_string_value) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1177,6 +1233,7 @@ TEST_F(URITemplateRouterViewTest, arguments_string_with_slashes) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1208,6 +1265,7 @@ TEST_F(URITemplateRouterViewTest, arguments_string_with_utf8) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1239,6 +1297,7 @@ TEST_F(URITemplateRouterViewTest, arguments_string_with_nulls) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1272,6 +1331,7 @@ TEST_F(URITemplateRouterViewTest, arguments_long_string_value) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1307,6 +1367,7 @@ TEST_F(URITemplateRouterViewTest, arguments_multiple_mixed_types) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1351,6 +1412,7 @@ TEST_F(URITemplateRouterViewTest, arguments_multiple_strings) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1393,6 +1455,7 @@ TEST_F(URITemplateRouterViewTest, arguments_multiple_integers) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1439,6 +1502,7 @@ TEST_F(URITemplateRouterViewTest, arguments_five_arguments) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1493,6 +1557,7 @@ TEST_F(URITemplateRouterViewTest, arguments_two_routes_different_args) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
 
   EXPECT_ROUTER_MATCH(restored, "/first", 1, captures_first);
   std::vector<std::pair<std::string_view,
@@ -1541,6 +1606,7 @@ TEST_F(URITemplateRouterViewTest, arguments_three_routes_one_without_args) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
 
   EXPECT_ROUTER_MATCH(restored, "/alpha", 1, captures_alpha);
   std::vector<std::pair<std::string_view,
@@ -1590,6 +1656,7 @@ TEST_F(URITemplateRouterViewTest, arguments_empty_router) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
 
   std::vector<std::pair<std::string_view,
                         sourcemeta::core::URITemplateRouter::ArgumentValue>>
@@ -1611,6 +1678,7 @@ TEST_F(URITemplateRouterViewTest, arguments_route_without_arguments) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/test", 1, captures);
 
   std::vector<std::pair<std::string_view,
@@ -1636,6 +1704,7 @@ TEST_F(URITemplateRouterViewTest, arguments_identifier_not_found) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
 
   std::vector<std::pair<std::string_view,
                         sourcemeta::core::URITemplateRouter::ArgumentValue>>
@@ -1660,6 +1729,7 @@ TEST_F(URITemplateRouterViewTest, arguments_identifier_zero) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
 
   std::vector<std::pair<std::string_view,
                         sourcemeta::core::URITemplateRouter::ArgumentValue>>
@@ -1684,6 +1754,7 @@ TEST_F(URITemplateRouterViewTest, arguments_with_variable_capture) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/users/42", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "42");
@@ -1717,6 +1788,7 @@ TEST_F(URITemplateRouterViewTest, arguments_with_expansion) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/files/a/b/c", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "a/b/c");
@@ -1758,6 +1830,7 @@ TEST_F(URITemplateRouterViewTest, arguments_multiple_routes_match_and_args) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
 
   EXPECT_ROUTER_MATCH(restored, "/users/1", 1, captures_users);
   EXPECT_EQ(captures_users.size(), 1);
@@ -1818,6 +1891,7 @@ TEST_F(URITemplateRouterViewTest, arguments_do_not_affect_match_precedence) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
 
   EXPECT_ROUTER_MATCH(restored, "/users/me", 1, captures_me);
   EXPECT_EQ(captures_me.size(), 0);
@@ -1875,6 +1949,7 @@ TEST_F(URITemplateRouterViewTest, arguments_survive_large_trie) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
 
   EXPECT_ROUTER_MATCH(restored, "/api/v1/alpha", 1, captures_alpha);
   EXPECT_ROUTER_MATCH(restored, "/api/v1/beta", 2, captures_beta);
@@ -1938,6 +2013,7 @@ TEST_F(URITemplateRouterViewTest, base_path_single_segment) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_EQ(restored.base_path(), "/prefix");
   EXPECT_ROUTER_MATCH(restored, "/prefix/foo", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -1950,6 +2026,7 @@ TEST_F(URITemplateRouterViewTest, base_path_without_prefix_no_match) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_EQ(restored.base_path(), "/prefix");
   EXPECT_ROUTER_MATCH(restored, "/foo", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -1963,6 +2040,7 @@ TEST_F(URITemplateRouterViewTest, base_path_multi_segment) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_EQ(restored.base_path(), "/v1/catalog");
   EXPECT_ROUTER_MATCH(restored, "/v1/catalog/api/list", 1, captures_list);
   EXPECT_EQ(captures_list.size(), 0);
   EXPECT_ROUTER_MATCH(restored, "/v1/catalog/foo/bar", 2, captures_expansion);
@@ -1978,6 +2056,7 @@ TEST_F(URITemplateRouterViewTest, base_path_with_variable) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_EQ(restored.base_path(), "/prefix");
   EXPECT_ROUTER_MATCH(restored, "/prefix/users/42", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "id", "42");
@@ -1991,6 +2070,7 @@ TEST_F(URITemplateRouterViewTest, base_path_prefix_boundary_no_match) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_EQ(restored.base_path(), "/prefix");
   EXPECT_ROUTER_MATCH(restored, "/prefixfoo", 0, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -2003,6 +2083,7 @@ TEST_F(URITemplateRouterViewTest, base_path_with_empty_template) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_EQ(restored.base_path(), "/v1/catalog");
   EXPECT_ROUTER_MATCH(restored, "/v1/catalog", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -2015,6 +2096,7 @@ TEST_F(URITemplateRouterViewTest, base_path_no_base_path_unchanged) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_TRUE(restored.base_path().empty());
   EXPECT_ROUTER_MATCH(restored, "/foo", 1, captures);
   EXPECT_EQ(captures.size(), 0);
 }
@@ -2027,7 +2109,35 @@ TEST_F(URITemplateRouterViewTest, base_path_expansion) {
   }
 
   const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_EQ(restored.base_path(), "/api");
   EXPECT_ROUTER_MATCH(restored, "/api/files/a/b/c", 1, captures);
   EXPECT_EQ(captures.size(), 1);
   EXPECT_ROUTER_CAPTURE(captures, 0, "path", "a/b/c");
 }
+
+TEST_F(URITemplateRouterViewTest, base_path_trailing_slash_normalized) {
+  {
+    sourcemeta::core::URITemplateRouter router{"/prefix/"};
+    router.add("/foo", 1);
+    sourcemeta::core::URITemplateRouterView::save(router, this->path);
+  }
+
+  const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_EQ(restored.base_path(), "/prefix");
+  EXPECT_ROUTER_MATCH(restored, "/prefix/foo", 1, captures);
+  EXPECT_EQ(captures.size(), 0);
+}
+
+TEST_F(URITemplateRouterViewTest,
+       base_path_multiple_trailing_slashes_normalized) {
+  {
+    sourcemeta::core::URITemplateRouter router{"/prefix///"};
+    router.add("/foo", 1);
+    sourcemeta::core::URITemplateRouterView::save(router, this->path);
+  }
+
+  const sourcemeta::core::URITemplateRouterView restored{this->path};
+  EXPECT_EQ(restored.base_path(), "/prefix");
+  EXPECT_ROUTER_MATCH(restored, "/prefix/foo", 1, captures);
+  EXPECT_EQ(captures.size(), 0);
+}