DevPost - API Debugger for DevTools

API debugger inside Chrome DevTools. Send requests, capture network traffic, manage collections and environments — no tab switching.

You're deep in a debugging session, chasing down a broken API call — and every second spent switching to Postman, copying URLs, and switching back is flow you never get back. DevPost eliminates that break. DevPost is an all-in-one API debugging platform that lives permanently inside Chrome DevTools. Press F12, and the DevPost panel is right next to the Network tab — the page, the requests, the debugging, mock servers, code generation, all in one window. ─── Core Features ─── ▸ Request Builder Full HTTP method support (GET/POST/PUT/DELETE/PATCH/HEAD/OPTIONS). Configure query params, headers, and request bodies (JSON / form-data / URL-encoded / XML / Raw / Binary file upload). Basic Auth, Bearer Token, API Key, and OAuth 2.0 (4 grant types with PKCE) built in. Import any request from cURL in one click. ▸ Network Capture Intercept HTTP/HTTPS requests made by the current page in real time. Inspect, edit, and replay captured requests directly in DevPost. Start and stop capture whenever you need it — no more copy-pasting cURL back and forth. ▸ WebSocket Debugging Full WebSocket support: connection management, message send/receive, JSON formatting, and connection history for effortless real-time communication debugging. ▸ SSE Streaming Responses Designed for AI models: automatic OpenAI/Gemini format detection, typing cursor effect, real-time display of AI-generated content. The best tool for debugging LLM API streaming responses. ▸ Local Mock Server Built-in mock server: custom mock responses with condition matching (URL pattern + HTTP method), delay simulation (0-10000ms), and status code configuration. Develop your frontend independently, no backend required. ▸ Code Generation One-click export requests to 9 languages and frameworks. ▸ Collections Save requests into nested folders with drag-and-drop sorting and right-click context menus. Support collection import/export and one-click migration from Postman, Insomnia, and Apifox. ▸ Environment & Dynamic Variables Create multiple environments (dev/staging/prod). Reference variables with {{VARIABLE_NAME}} syntax. Built-in dynamic variables: $timestamp, $uuid, $randomInt, $randomFloat, $randomString, $date — auto-generated fresh on every send. ▸ Request Version History Automatically records every modification. Revert to any previous version and view Diff comparisons between versions. Never worry about losing your work. ▸ Multi-Tab Editing Open multiple request tabs simultaneously with support for pinning, closing, and drag-to-reorder tabs. Effortlessly switch between APIs. ▸ Script Automation Pre-request and Post-response scripts using a Postman-like pm API: dynamically modify requests, parse responses, and set environment variables. ▸ Response Viewer JSON syntax highlighting + pretty-print + tree view, XML tree view, HTML live preview, image inline rendering, PDF embedded viewer. Response search with highlighting, case-sensitivity, and regex. Cookie management with full attribute details. ▸ Timeline Visualization Full request phase timing: DNS lookup, TCP connection, TLS handshake, TTFB (Time to First Byte), and download time — spot performance bottlenecks at a glance. ▸ OpenAPI / Swagger Import Import OpenAPI 3.0 and Swagger 2.0 specification files (JSON/YAML). Automatically parses all endpoints and generates collections by tag. ▸ 22 Languages UI language follows your browser locale by default. Supports 22 languages covering major global users. ─── Privacy ─── DevPost does not collect, transmit, or store any user data outside of your local browser. All request data, collections, environment variables, and history are saved exclusively in chrome.storage.local on your own device. No analytics, no telemetry, no external servers, no account required. ─── Permissions ─── • storage — saves your collections, history, environment variables, and settings locally • contextMenus — adds a right-click option to import selected cURL text directly • host_permissions (<all_urls>) — required to capture and proxy network requests on any domain you choose to debug ─── How to Use ─── 1. Install the extension 2. Open Chrome DevTools (F12 or right-click → Inspect) 3. Click the "DevPost" panel tab 4. Build and send your first request — or click "Capture" to intercept live traffic ─── Keyboard Shortcuts ─── • Ctrl+F — Global search • Ctrl+S — Save current request • Ctrl+Enter — Send request