Introducing Rex — A REST API Client in Your Browser
Meet Rex: a full-featured, keyboard-driven API client Chrome extension with collections, environments, auth, scripting, WebSocket support, and code generation.
Why Another API Client?
Desktop API clients are powerful, but they’re also heavyweight. You install a 500MB Electron app, create an account, sync to someone else’s cloud, and wait for it to boot every time you need to test an endpoint. For something you do fifty times a day, that’s a lot of friction.
Rex is different. It’s a Chrome extension. It opens instantly, stores everything locally, and doesn’t need an account.
What Is Rex?
Rex is a full-featured REST API client that lives in your browser. It handles everything you’d expect from a desktop client — request building, collections, environments, authentication, scripting, and code generation — without the overhead.
Core Features
Request Builder. A visual editor for HTTP requests with tabbed panels for params, headers, body (JSON, form-data, GraphQL, URL-encoded, raw), auth, scripts, and cookies. Paste a cURL command and Rex auto-parses it into a full request.
Collections & Tabs. Save requests into named collections. Work on multiple requests in parallel tabs. Drag and drop to reorder. Everything persists across sessions in IndexedDB.
Environments & Variables. Define variable sets for dev, staging, and production. Use {{variable}} syntax anywhere — URLs, headers, body, auth. Switch environments with one click.
7 Auth Methods. Bearer, Basic, API Key, OAuth 2.0 (authorization code, client credentials, PKCE with automatic token refresh), AWS Signature V4, Digest, and mTLS — all built in.
Pre-Request & Test Scripts. A JavaScript API for modifying requests before sending and asserting on responses after. Set variables dynamically, extract values from responses, and chain dependent calls with pass/fail reporting.
WebSocket & SSE. Connect to WebSocket endpoints for real-time bidirectional messaging. Stream Server-Sent Events with auto-scroll and payload inspection.
What Else?
- Code generation — Generate working snippets in JavaScript (Fetch, Axios, Node.js), Python (requests, httpx), and cURL
- Import & export — Postman collections, OpenAPI/Swagger, HAR, cURL, and Rex’s native format
- Response rendering — JSON with syntax highlighting, inline HTML preview, image display, PDF viewer, XML formatting, hex dump for binary
- Request chaining — Build sequences of dependent requests with variable extraction, failure handling, and retry logic
- DevTools panel — Capture live network requests from any page and send them to Rex or bulk import as a collection
- History & diff — Every request logged automatically with full search and side-by-side comparison
- GraphQL — Schema introspection with autocomplete for types, fields, queries, and mutations
- Cookie editor — View, inspect, and delete cookies for any domain
- API docs viewer — Load OpenAPI/Swagger specs and browse endpoints with a “Try it” button
Keyboard-Driven
Rex is built for developers who prefer the keyboard:
| Action | Shortcut |
|---|---|
| Send | Cmd+Enter |
| Save | Cmd+S |
| Toggle sidebar | Cmd+B |
Privacy
Everything stays on your machine. All data is stored in IndexedDB and localStorage. No accounts, no cloud sync, no telemetry. The extension’s host permissions exist solely to send requests to the endpoints you specify.
Get Started
Rex is available on the Chrome Web Store. Install it, open the popup, and start building requests.
Learn more: Rex product page · Documentation