API Generator
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380+ models
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Model:
+ GPT-5, Claude, Gemini
Describe a REST API and get back a complete endpoint scaffold — route handlers, Pydantic/Zod schemas, auth middleware, OpenAPI spec, tests, and a curl reference. Pick framework (FastAPI, Express, Next.js, Django REST, Flask, NestJS, Go chi, Rails, Laravel), auth style (JWT / API key / OAuth2), and response format (JSON / MessagePack).
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Generate REST API code with free AI. Endpoints, schemas, and documentation.
How to Use API Generator
1
Enter your input
Type text, upload a file, or describe what you want. No account needed.
2
Click generate
Our AI processes your request in seconds using the best open-source models.
3
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Download, copy, or share your result. Free for personal and commercial use.
Use this tool via API
Automate this tool from your own code. OpenAI-compatible REST endpoint, Bearer-token auth, no extra SDK required. Token costs match the web interface.
curl -X POST https://api.free.ai/v1/chat/ \
-H "Authorization: Bearer sk-free-..." \
-H "Content-Type: application/json" \
-d '{"model": "qwen-coder", "messages": [{"role": "user", "content": "Write a Python function that reverses a string."}]}'API Generator — FAQ
Describe a set of endpoints and get back a complete scaffold in your chosen framework — handlers, request/response schemas, auth middleware, error handlers, OpenAPI spec, tests, and curl examples. 15 frameworks supported (FastAPI, Flask, Django REST, Express, Next.js, NestJS, Hono, Go chi, Go stdlib 1.22 ServeMux, Rails, Laravel, Spring Boot, ASP.NET Core, Axum, Elysia). 6 auth styles (no auth, API key, JWT Bearer, OAuth 2.0, HTTP Basic, session cookie).
Swagger Codegen / OpenAPI Generator work the OTHER direction — they generate clients / servers from an existing spec. Free.ai writes the first-draft spec AND the implementation from a plain-English description. NSwag is .NET-specific. Complementary workflow: Free.ai gets you the initial scaffold + OpenAPI in one shot, then OpenAPI Generator produces language-bindings for clients in 40+ languages.
Bolt.new ($20/mo after free tier) and v0.dev ($20/mo after free) focus on full-stack / frontend generation. Cursor ($20/mo) is an IDE for AI pair-programming. Free.ai is backend-API-specific and 100% free under the daily token pool — purpose-built prompts for REST conventions, auth patterns, OpenAPI emission, and realistic test-suite shape.
Usually yes for the framework skeleton — the scaffolding (imports, router setup, middleware) is tested at the prompt level. The business logic uses TODO placeholders where you need to wire DB/queue/external services. Plan for 10-20 min of integration after paste: fill DB queries, replace fake JWT secret, run your own migrations.
FastAPI for Python new projects (best DX, auto-OpenAPI). Express or Hono for Node.js (Express: mature + huge ecosystem; Hono: edge-ready). Next.js App Router if already on Next.js. NestJS if you want Angular-style DI + decorators. Go chi for Go (idiomatic, lightweight); Go stdlib 1.22 ServeMux if zero-deps. Rails / Laravel / Spring Boot / ASP.NET Core for existing stacks. Axum for Rust. Elysia for Bun.
Yes — emitted as OpenAPI 3.1 YAML with proper components/schemas using $ref, responses with at-least 200 + 4xx per operation, and security schemes matching the chosen auth. Validate with Redocly CLI or swagger-cli before committing. If your framework auto-generates OpenAPI (FastAPI, NestJS @nestjs/swagger), the hand-written spec is a starting point for customization.
A test file using the framework's idiomatic tester: pytest + httpx.AsyncClient for FastAPI, supertest for Express, @nestjs/testing for NestJS, httptest for Go, RSpec for Rails, XCTest pattern for Swift-Vapor, etc. Covers one happy-path per endpoint + an auth-failure test. Not exhaustive — use /code/test/ for deeper coverage.
JWT Bearer for most SaaS APIs (stateless, scales horizontally). API key for internal tools (simplest, rotate manually). OAuth 2.0 when integrating with identity providers (Google, GitHub, Auth0). HTTP Basic for quick internal scripts (insecure over HTTP — always HTTPS). Session cookie for browser-first apps where JWT is overkill. The generated code includes the minimum-viable verification — always review before shipping.
Yes when you ask for it. Mention "SSE" or "WebSocket" in the description and the generated code uses the framework's idiomatic mechanism (StreamingResponse in FastAPI, res.setHeader + flush for Express, server-sent-events helper for Next.js, upgrades for Hono/Axum). For WebSocket-heavy apps, consider dedicated libraries (Socket.IO, Ably).
The generated middleware is a starting point — uses an in-memory store by default, fine for single-process apps. For multi-instance deployments switch to Redis (every rate-limit lib supports a Redis backend — see the library's docs). The TODO comment in the generated code flags this.
The description is sent to the model, processed, and discarded. Not stored, not used for training. For maximum privacy pick Qwen 3 Coder — self-hosted on Free.ai's GPUs. Premium external models (Claude, GPT-5) route through their providers under their data-handling terms.
Yes — POST to /v1/chat/ with the API-generator system prompt (framework + auth + extras) and your description as the user message. Useful for project-scaffolding CLIs that generate API boilerplate from a spec. See /api/.
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