HTTP & API Tools

Free browser-based tools for building, debugging, and inspecting HTTP requests. Complete reference for status codes, headers, methods, and cURL examples — no sign-up, no server round-trips.

HTTP is the foundation of the web, and understanding it deeply makes every area of development easier. This collection covers the full HTTP lifecycle: building requests with the API Request Builder, generating and parsing cURL commands, inspecting response headers with the Header Viewer, and parsing Set-Cookie headers to understand exactly what a server is setting in the browser.

The HTTP status code reference covers all 60+ codes across every class: 1xx informational responses, 2xx success codes, 3xx redirections, 4xx client errors, and 5xx server errors. Each status code page explains what the code means, lists the most common causes, suggests fixes, and provides a raw HTTP example. The 404, 401, 403, 500, and 503 pages include extended troubleshooting guidance for the most frequently encountered errors.

The header reference documents the 25 most important HTTP request and response headers, including security headers like Strict-Transport-Security, X-Content-Type-Options, and X-Frame-Options. The CORS and redirect checkers are particularly useful for debugging cross-origin issues and verifying that redirect chains are behaving as expected — both common sources of hard-to-diagnose bugs in production web applications.

Interactive Tools

API Request Builder

Build & test HTTP requests visually

cURL Generator

Generate & parse cURL commands

HTTP Header Viewer

Inspect HTTP response headers

Get Page Title

Fetch HTML & Open Graph title from any URL

HTTP Header Diff

Compare two sets of HTTP headers

HTTP Status Lookup

Look up HTTP status codes & fixes

CORS Checker

Check CORS headers for any URL

Redirect Checker

Follow & inspect redirect chains

Cookie Parser

Parse & build Set-Cookie headers

URL Query Parser

Parse & build URL query strings

URL Encoder / Decoder

Encode & decode URL components

HTTP Status Codes

100 Continue 101 Switching Protocols 102 Processing 103 Early Hints 200 OK 201 Created 202 Accepted 203 Non-Authoritative Info 204 No Content 205 Reset Content 206 Partial Content 207 Multi-Status 208 Already Reported 226 IM Used 300 Multiple Choices 301 Moved Permanently 302 Found 303 See Other 304 Not Modified 305 Use Proxy 307 Temporary Redirect 308 Permanent Redirect 400 Bad Request 401 Unauthorized 402 Payment Required 403 Forbidden 404 Not Found 405 Method Not Allowed 406 Not Acceptable 407 Proxy Auth Required 408 Request Timeout 409 Conflict 410 Gone 411 Length Required 412 Precondition Failed 413 Payload Too Large 414 URI Too Long 415 Unsupported Media Type 416 Range Not Satisfiable 417 Expectation Failed 418 I'm a Teapot 421 Misdirected Request 422 Unprocessable Entity 423 Locked 424 Failed Dependency 425 Too Early 426 Upgrade Required 428 Precondition Required 429 Too Many Requests 431 Header Fields Too Large 451 Unavailable For Legal Reasons 500 Internal Server Error 501 Not Implemented 502 Bad Gateway 503 Service Unavailable 504 Gateway Timeout 505 HTTP Version Not Supported 506 Variant Also Negotiates 507 Insufficient Storage 508 Loop Detected 510 Not Extended 511 Network Auth Required

HTTP Methods

GET POST PUT PATCH DELETE HEAD OPTIONS TRACE CONNECT

MIME Types

application/json application/xml text/html text/css text/javascript image/png image/jpeg application/pdf Full MIME Types Reference

Discovery Pages

All Tools All Linux Commands All JS Methods All CSS Properties All Emoji

About DuskTools HTTP & API Tools

DuskTools provides a complete, free HTTP reference and toolset built for modern web developers. Browse every standard HTTP status code — from informational 1xx responses through successful 2xx, redirection 3xx, client error 4xx, and server error 5xx — with human-readable descriptions, common causes, and practical debugging tips for each. Our HTTP headers reference covers 25 of the most important headers including Authorization, Content-Type, Cache-Control, CORS-related headers, and security headers like Strict-Transport-Security and X-Content-Type-Options. Explore all nine HTTP methods with detailed explanations of when to use GET versus POST, the semantics of PUT versus PATCH, and the purpose of less-common methods like OPTIONS and TRACE. For API testing, the cURL examples section provides 20 copy-paste-ready snippets covering JSON payloads, file uploads, authentication patterns, proxy configuration, and more. Each interactive tool — from the API Request Builder to the Cookie Parser — runs entirely in your browser so sensitive tokens and credentials never leave your machine. Whether you are debugging a 502 Bad Gateway, configuring CORS headers, or building a REST client, DuskTools gives you the references and utilities you need in one fast, dark-mode-optimized interface.