Random Data Generator

A small Ruby library, a Sinatra JSON API and a TypeScript single-page UI for producing believable fake data on demand — built as a pet project to practice end-to-end Ruby + web tooling

What it does

The project exposes a catalog of generators — strings, numbers, dates, addresses, social data, URLs, UUIDs, colors — and lets you call them from three places: a Ruby library, an HTTP API, or a clickable web UI

A typical use case: you need a couple of plausible emails, a city, a UUID and a hex color while wiring up a demo, and you do not want to bring in Faker or write yet another helper script

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Architecture

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├── lib/random_data_generator/   # pure-Ruby generators (the core library)
├── api/                         # Sinatra app — wraps the library as JSON HTTP
├── web/                         # Vite + TypeScript + Tailwind single-page UI
├── resources/                   # plain-text dictionaries (cities, streets, prose)
├── spec/                        # RSpec — library and API specs
├── bin/                         # `demo` CLI and `server` launcher
└── .github/workflows/ci.yml     # lint, typecheck, tests, build for Ruby and Node

The library has no third-party runtime dependencies — pure standard library Ruby The API is a thin Sinatra layer that validates query params and serializes responses as JSON The frontend talks to the API over fetch, with Vite proxying /api/* to Sinatra in development

Quickstart

1. Run the library

bundle install
bundle exec ruby bin/demo

2. Run the API

bundle exec rackup -p 3000
# → http://localhost:3000
curl http://localhost:3000/api/health
curl 'http://localhost:3000/api/string/string?length=12'

3. Run the web UI

cd web
npm install
npm run dev
# → http://localhost:8080 (proxies /api to the Sinatra server on :3000)

For a production build, run npm run build inside web/ — the Sinatra app will serve the resulting web/dist/ automatically at /

Using the library directly

require 'random_data_generator'

RandomDataGenerator::StringGenerator.random_alpha_numeric_string(16)
RandomDataGenerator::SocialGenerator.random_email
RandomDataGenerator::AddressGenerator.random_address
RandomDataGenerator::OtherGenerator.random_date(Date.new(2020, 1, 1), Date.today)
RandomDataGenerator::OtherGenerator.random_uuid

HTTP API

Endpoint	Params	Example response
GET /api/health	—	{ "status": "ok", "version": "1.0.0" }
GET /api/generators	—	{ "generators": [...] }
GET /api/string/string	length (1..1024)	{ "value": "JtKfQwertyAb" }
GET /api/string/alpha_numeric	length	{ "value": "a7Kf9Q" }
GET /api/string/letter	length	{ "value": "asdfqwer" }
GET /api/social/email	—	{ "value": "asdfasdf@gmail.com" }
GET /api/social/phone_number	—	{ "value": "+1-415-555-0142" }
GET /api/social/ip_address	—	{ "value": "192.168.0.42" }
GET /api/social/person_name	—	{ "value": "Sarah Johnson" }
GET /api/social/animal_name	—	{ "value": "Otter-4231" }
GET /api/social/company_name	—	{ "value": "Nova LLC" }
GET /api/social/url	—	{ "value": "https://www.example421.io" }
GET /api/address/city	—	{ "value": "Berlin" }
GET /api/address/street_name	—	{ "value": "Sunset Boulevard" }
GET /api/address/house_number	—	{ "value": 742 }
GET /api/address/address	—	{ "value": "742 Sunset Blvd, Berlin" }
GET /api/address/coordinates	—	{ "value": { "latitude": ..., "longitude": ... } }
GET /api/other/number	min, max	{ "value": 73, "min": 1, "max": 100 }
GET /api/other/date	from, to (ISO)	{ "value": "2023-04-12" }
GET /api/other/color	—	{ "value": "#3A8FCB" }
GET /api/other/text_description	—	{ "value": "A quiet afternoon..." }
GET /api/other/boolean	—	{ "value": true }
GET /api/other/uuid	—	{ "value": "f8e1...8b9d" }

Errors are returned as JSON — 400 for invalid params, 404 for unknown routes, 500 with an error code otherwise

Tooling

Concern	Tool
Library tests	RSpec, Rack::Test
Ruby lint	RuboCop with the rubocop-rspec ext
Frontend tests	Vitest with jsdom
Frontend lint	ESLint with @typescript-eslint
Formatting	Prettier
Bundler	Vite 5
Styling	Tailwind CSS 3.4
CI	GitHub Actions (.github/workflows/ci.yml)

The CI matrix runs Ruby 3.2 and 3.3 plus Node 20 and 22 — every push and pull request runs lint, typecheck, tests and the production build for both halves of the codebase

Project layout in detail

lib/random_data_generator.rb               # public entry point
lib/random_data_generator/version.rb       # VERSION constant
lib/random_data_generator/string_generator.rb
lib/random_data_generator/social_generator.rb
lib/random_data_generator/address_generator.rb
lib/random_data_generator/other_generator.rb

api/app.rb                                 # Sinatra::Base subclass
api/config.ru                              # Rack entry for the api/ directory

config.ru                                  # root-level Rack entry — what `rackup` picks up

bin/demo                                   # prints one sample from every generator
bin/server                                 # boots the API without rackup

web/src/main.ts                            # SPA shell — filter, search, grid
web/src/components/generator-card.ts       # interactive card for one generator
web/src/components/toast.ts                # ephemeral feedback toasts
web/src/api.ts                             # typed fetch wrapper
web/src/generators.ts                      # catalog of generators surfaced in the UI
web/tests/api.test.ts                      # Vitest coverage for the API client

resources/cities.txt                       # ~500 city names
resources/street_names.txt                 # ~6000 street names
resources/descriptions.txt                 # ~50 prose snippets

Roadmap

• Open API / Swagger document generated from the route table
• Optional CSV / NDJSON bulk export (?count=100)
• Locale-aware names and addresses (?locale=ru)
• Dockerfile + docker-compose.yml for one-line setup