Free Developer Tools

Fake REST API

Free hosted dummy JSON API — users, posts, comments, todos and products. JSONPlaceholder-compatible pagination, filtering and CORS. Call it from any app, no signup or API key.

API Tester NEW

Send HTTP requests to any API endpoint and inspect the full response — status code, headers, body and timing. Supports GET, POST, PUT, PATCH, DELETE. Import cURL commands, view request history, and test MockServer's Fake REST API with CORS enabled.

JSON to Code NEW

Paste JSON and instantly generate typed code — TypeScript interfaces, Go structs, Python dataclasses, Rust, Swift, Java, Kotlin, C#, and Dart. Runs entirely in your browser.

cURL to Code NEW

Paste a curl command and instantly get equivalent code in JavaScript (fetch, axios), Python, Go, PHP, Ruby, Java, C#, Rust, Swift, and Kotlin. Runs entirely in your browser.

Regex Tester

Write a regular expression and paste a test string to instantly see every match highlighted in real time. Supports global, case-insensitive, multiline, and dotall flags with captured group display.

Cron Expression Parser

Enter any cron schedule and get a plain-English description plus the next 10 run times in your local timezone. Includes quick presets for the most common schedules.

Epoch / Unix Timestamp Converter

Convert a Unix timestamp to UTC, ISO 8601, local time, and relative time — or convert any date back to epoch. Auto-detects milliseconds vs seconds.

UUID Generator

Generate cryptographically random UUID v4s or time-ordered UUID v7s in bulk (up to 100 at once). Choose format: standard, uppercase, no-hyphens, or with braces.

Hash Generator

Compute MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes from any text instantly. Output in lowercase hex or uppercase. All hashing runs locally — your data never leaves the browser.

Base64 Encoder / Decoder

Encode text or binary to Base64, or decode a Base64 string back to readable text. Supports full Unicode/UTF-8. Nothing leaves your browser.

URL Encoder / Decoder

Percent-encode URLs and query strings, or decode them back to plain text. Supports both encodeURIComponent (query values) and encodeURI (full URLs).

JSON Formatter

Paste minified or messy JSON and get clean, indented, pretty-printed output instantly. Validates syntax and shows the exact line of any error. Keyboard shortcut: Ctrl+Enter.

JSON Beautifier

Transform compressed single-line JSON into readable indented format with configurable spacing. Shows a before/after size comparison and supports copy or download of the result.

JSON Diff

Paste two JSON objects side by side and instantly see every added, removed, and changed key highlighted with a color-coded diff tree.

JSON Repair

Auto-fix broken JSON — trailing commas, single quotes, unquoted keys, Python literals, missing brackets. If it can't be repaired, the exact error line is highlighted so you can fix it manually.

JSON Minify

Shrink JSON to a single compact line for production payloads or API requests. Shows original size, output size, and percentage reduction.

JWT Decoder

Decode and inspect any JSON Web Token — header, payload, and claims. Shows expiry status, issued-at time, and all standard claims in a readable format. Nothing leaves your browser.

JSON Validator

Validate JSON in real time as you type. On error, pinpoints the exact line and column with the offending content. On success, shows a full stats breakdown: size, key count, depth, arrays, and objects.