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API developer tools

Practical tools that run in your browser and teach as you use them. Your data stays on your device unless you choose otherwise.

App Builder

Create a real API without code, drag together a live front end, call it from your own computer and download the finished app.

Endpoint Client

A full API client in your browser: collections, environments, curl and Postman import, tests, chaining, a collection runner and a Security Lens on every response.

API readiness audit

Grade an OpenAPI document for documentation, design, security and AI-agent readiness. Export Model Context Protocol tools.

JWT decoder and security checker

Decode tokens, check claims and expiry, and detect well-known signing secrets, all locally.

Practice API

Free endpoints for echo, any status code, delays, pagination with ETags, and a token flow. CORS is open.

HTTP reference

Every status code and common header explained in plain language, with what your client should do next.