diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9e78ae7..3c5a9f0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## Next
 
+* Added `Transloadit-Client` headers with the SDK name and version to assembly creation, status, and cancellation requests.
 * Added `tusUploadChunkSize` to Transloadit initializers so apps can tune TUS chunking behavior, including single-request uploads with `0`.
 * Clarified that `createAssembly(... andUpload ..., completion:)` completes after upload scheduling, not after file upload or processing completion.
 
diff --git a/Sources/TransloaditKit/TransloaditAPI.swift b/Sources/TransloaditKit/TransloaditAPI.swift
index eb3de91..9929c6a 100644
--- a/Sources/TransloaditKit/TransloaditAPI.swift
+++ b/Sources/TransloaditKit/TransloaditAPI.swift
@@ -22,6 +22,9 @@ enum TransloaditAPIError: Error {
 final class TransloaditAPI: NSObject {
     
     private let basePath = URL(string: "https://api2.transloadit.com")!
+
+    // Keep this version in sync with Transloadit.podspec when releasing; header tests enforce it.
+    private static let clientHeader = "transloaditkit:3.5.0"
     
     enum Endpoint: String {
         case assemblies = "/assemblies"
@@ -180,7 +183,10 @@ final class TransloaditAPI: NSObject {
         let path = basePath.appendingPathComponent(Endpoint.assemblies.rawValue)
         var request: URLRequest = URLRequest(url: path, cachePolicy: .reloadIgnoringLocalAndRemoteCacheData, timeoutInterval: 30)
         
-        let headers = ["Content-Type": String(format: "multipart/form-data; boundary=%@", boundary)]
+        let headers = [
+            "Content-Type": String(format: "multipart/form-data; boundary=%@", boundary),
+            "Transloadit-Client": Self.clientHeader
+        ]
         
         request.httpMethod = "POST"
         request.allHTTPHeaderFields = headers
@@ -281,6 +287,7 @@ final class TransloaditAPI: NSObject {
         func makeRequest() -> URLRequest {
             var request = URLRequest(url: assemblyURL, cachePolicy: .reloadIgnoringLocalAndRemoteCacheData)
             request.httpMethod = "GET"
+            request.setValue(Self.clientHeader, forHTTPHeaderField: "Transloadit-Client")
             return request
         }
         
@@ -307,6 +314,7 @@ final class TransloaditAPI: NSObject {
         func makeRequest() -> URLRequest {
             var request = URLRequest(url: assembly.url, cachePolicy: .reloadIgnoringLocalAndRemoteCacheData)
             request.httpMethod = "DELETE"
+            request.setValue(Self.clientHeader, forHTTPHeaderField: "Transloadit-Client")
             return request
         }
         
diff --git a/Tests/TransloaditKitTests/TransloaditAPIHeaderTests.swift b/Tests/TransloaditKitTests/TransloaditAPIHeaderTests.swift
new file mode 100644
index 0000000..6f8808d
--- /dev/null
+++ b/Tests/TransloaditKitTests/TransloaditAPIHeaderTests.swift
@@ -0,0 +1,122 @@
+import Foundation
+import XCTest
+@testable import TransloaditKit
+
+final class TransloaditAPIHeaderTests: XCTestCase {
+    private var api: TransloaditAPI!
+    private var expectedClientHeader = ""
+
+    override func setUpWithError() throws {
+        try super.setUpWithError()
+        // Check the transmitted version against release metadata to catch version drift.
+        let repoURL = URL(fileURLWithPath: #filePath)
+            .deletingLastPathComponent()
+            .deletingLastPathComponent()
+            .deletingLastPathComponent()
+        let podspec = try String(contentsOf: repoURL.appendingPathComponent("Transloadit.podspec"), encoding: .utf8)
+        let versionPattern = try NSRegularExpression(pattern: #"s\.version\s*=\s*['"]([^'"]+)['"]"#)
+        let versionMatch = try XCTUnwrap(
+            versionPattern.firstMatch(in: podspec, range: NSRange(location: 0, length: podspec.utf16.count)),
+            "Transloadit.podspec must declare an SDK version"
+        )
+        let versionRange = try XCTUnwrap(Range(versionMatch.range(at: 1), in: podspec))
+        expectedClientHeader = "transloaditkit:\(podspec[versionRange])"
+        MockURLProtocol.reset()
+
+        let configuration = URLSessionConfiguration.ephemeral
+        configuration.protocolClasses = [MockURLProtocol.self]
+        configuration.httpAdditionalHeaders = ["X-Test-Header": "preserved"]
+        api = TransloaditAPI(
+            credentials: .init(key: "test-key", secret: nil),
+            sessionConfiguration: configuration,
+            signatureGenerator: { _, completion in
+                completion(.success("test-signature"))
+            }
+        )
+    }
+
+    override func tearDown() {
+        api = nil
+        MockURLProtocol.reset()
+        super.tearDown()
+    }
+
+    func testCreateAssemblySendsClientHeader() {
+        let assembly = Fixtures.makeAssembly()
+        prepareResponse(
+            for: URL(string: "https://api2.transloadit.com/assemblies")!,
+            method: "POST",
+            data: Fixtures.makeAssemblyResponse(assembly: assembly)
+        )
+        let completed = expectation(description: "Assembly created")
+
+        api.createAssembly(steps: [], expectedNumberOfFiles: 0, customFields: [:]) { result in
+            switch result {
+            case .success(let receivedAssembly):
+                XCTAssertEqual(receivedAssembly, assembly)
+            case .failure(let error):
+                XCTFail("Creating an assembly failed: \(error)")
+            }
+            completed.fulfill()
+        }
+
+        wait(for: [completed], timeout: 3)
+    }
+
+    func testFetchStatusSendsClientHeader() {
+        let assembly = Fixtures.makeAssembly()
+        prepareResponse(
+            for: assembly.url,
+            method: "GET",
+            data: Fixtures.makeAssemblyStatusResponse(assemblyStatus: Fixtures.makeAssemblyStatus(status: .completed))
+        )
+        let completed = expectation(description: "Status fetched")
+
+        api.fetchStatus(assemblyURL: assembly.url) { result in
+            switch result {
+            case .success(let status):
+                XCTAssertEqual(status.processingStatus, .completed)
+            case .failure(let error):
+                XCTFail("Fetching status failed: \(error)")
+            }
+            completed.fulfill()
+        }
+
+        wait(for: [completed], timeout: 3)
+    }
+
+    func testCancelAssemblySendsClientHeader() {
+        let assembly = Fixtures.makeAssembly()
+        prepareResponse(
+            for: assembly.url,
+            method: "DELETE",
+            data: Fixtures.makeAssemblyStatusResponse(assemblyStatus: Fixtures.makeAssemblyStatus(status: .canceled))
+        )
+        let completed = expectation(description: "Assembly canceled")
+
+        api.cancelAssembly(assembly) { result in
+            switch result {
+            case .success(let status):
+                XCTAssertEqual(status.processingStatus, .canceled)
+            case .failure(let error):
+                XCTFail("Canceling an assembly failed: \(error)")
+            }
+            completed.fulfill()
+        }
+
+        wait(for: [completed], timeout: 3)
+    }
+
+    private func prepareResponse(for url: URL, method: String, data: Data) {
+        let expectedClientHeader = self.expectedClientHeader
+        MockURLProtocol.prepareResponse(for: url, method: method) { headers in
+            XCTAssertEqual(headers?["Transloadit-Client"], expectedClientHeader)
+            // Session headers should survive adding SDK request headers on supported Apple platforms.
+            XCTAssertEqual(headers?["X-Test-Header"], "preserved")
+            if method == "POST" {
+                XCTAssertTrue(headers?["Content-Type"]?.hasPrefix("multipart/form-data; boundary=") == true)
+            }
+            return MockURLProtocol.Response(status: 200, headers: [:], data: data)
+        }
+    }
+}