APIs power modern web and mobile apps. But working with APIs requires testing, debugging, and documentation. Paid tools like Postman Pro can be expensive.
Here are 10 free API tools that cover everything from testing to monitoring.
1. Postman (Free tier) – API Testing
URL: https://postman.com
Postman is the industry standard for API testing. The free tier includes unlimited API requests, collections, workspaces, and request history. You can organize requests into collections, add tests, and automate workflows.
For individual developers, the free version is more than enough. The paid version adds team collaboration, API documentation, and monitoring.
2. Hoppscotch – Lightweight Postman Alternative
URL: https://www.baike300.com/article/55.html
Hoppscotch is a free, open‑source, web‑based API client. It's lightweight and fast. No installation needed – just open your browser. Supports GraphQL, WebSockets, and server‑sent events.
If you find Postman too heavy, Hoppscotch is a great alternative. The UI is clean and modern.
3. Insomnia – Open‑Source API Client
Insomnia is another popular API client. It's open‑source and supports GraphQL, gRPC, and WebSockets. The free version includes unlimited requests, environment variables, and plugin support.
Insomnia's design focuses on developer experience. The interface is intuitive and less cluttered than Postman.
4. Swagger UI – API Documentation
URL: https://swagger.io/tools/swagger-ui/
Swagger UI generates interactive API documentation from OpenAPI specifications. Users can test endpoints directly from the documentation page.
It's free, open‑source, and widely adopted. If you're building an API, Swagger UI is the standard for documentation.
5. Stoplight (Free tier) – API Design
URL: https://stoplight.io
Stoplight helps you design, document, and mock APIs. The free tier includes API design with OpenAPI, visual editors, and mock servers.
For planning APIs before writing code, Stoplight is excellent. The visual editor makes OpenAPI approachable.
6. Beeceptor – Mock API Server
Beeceptor creates mock API endpoints instantly. You can simulate responses, delay responses, and inspect incoming requests. The free tier includes 50 requests per day.
When the backend API isn't ready, Beeceptor lets you build the frontend anyway. Great for prototyping.
7. httpbin – HTTP Request Testing
URL: https://httpbin.org
httpbin is a simple HTTP request and response service. It returns data about your request: headers, IP, user‑agent, etc.
It's free, open‑source, and invaluable for testing HTTP clients, webhooks, and API libraries. No registration required.
8. Webhook.site – Webhook Testing
URL: https://webhook.site
Webhook.site gives you a unique URL to catch and inspect webhooks. See the raw payload, headers, and timing. The free tier includes 100 requests per day.
Testing webhooks is painful without tools like this. Webhook.site shows exactly what was sent.
9. Public APIs – API Collection
Public APIs is a curated list of free APIs for developers. Categories include weather, finance, music, sports, and more.
Need a real‑world API to test your code? This collection saves hours of searching. All APIs are free or have free tiers.
10. APIToolkit (Free tier) – API Monitoring
APIToolkit monitors API traffic and alerts you to errors. The free tier includes 5,000 requests per month, 2 endpoints, and basic error monitoring.
For early‑stage projects, APIToolkit catches API issues before users notice. The paid version adds more features.
More resources: Check our technical tutorials or VPS reviews.