JSON Formatter, API Tester Kit

Free JSON formatter, REST API tester, JWT decoder, regex tester, hash generator, Base64 & URL encoder, timestamp converter and UUID generator — all in one lightweight Android app. The only mobile dev toolkit with a built-in REST API client.

Stop installing ten different utilities. Dev Toolkit puts every essential developer tool in one fast, offline-friendly app — built for Android developers, backend engineers, QA testers and DevOps.

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WHY DEVELOPERS PICK DEV TOOLKIT
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• 9 essential dev tools in 1 free app
• Built-in REST API tester — most multi-tool apps don't have one
• Most tools work fully offline
• Clean interface — no interruptive ads in the middle of your work
• One-tap copy & share
• Opens in under a second
• No sign-up required

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EVERY TOOL YOU NEED
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▸ JSON FORMATTER, VIEWER & VALIDATOR
The fastest JSON formatter for Android. Beautify, validate, minify and pretty-print JSON instantly with syntax highlighting — a powerful mobile alternative to JSONLint and online JSON viewers.
• Beautify & prettify JSON for readability
• Minify JSON for compact API payloads
• Built-in JSON validator with error highlighting
• Copy formatted output in one tap

▸ REST API TESTER (Postman alternative) — exclusive in this app
A lightweight HTTP client and REST API tester for Android. Send GET, POST, PUT, PATCH and DELETE requests with custom headers, query params and JSON bodies. The pocket-sized Postman alternative for debugging APIs on the go. Most multi-tool dev apps skip this — Dev Toolkit ships it as a first-class tool.
• Test REST APIs from your phone
• Custom headers and query parameters
• JSON request body support
• Pretty-formatted responses with status colors

▸ JWT DECODER (JSON Web Token)
Decode and inspect any JWT token instantly. View the header, payload, claims and expiry time — perfect for OAuth, Firebase Auth, bearer tokens and API debugging.
• Decode JWT header & payload
• Pretty-formatted JSON output
• View issued-at and expiry times
• Copy individual claims with one tap

▸ REGEX TESTER (Regular Expression)
Build and test regular expressions on the fly with live match highlighting — great for text parsing, log scraping and form validation.

▸ HASH GENERATOR (MD5, SHA-1, SHA-256, SHA-512)
Generate cryptographic hashes and checksums instantly for data integrity verification, password hashing demos and debugging.

▸ TIMESTAMP CONVERTER (Unix / Epoch time)
Convert Unix timestamps to readable dates and vice versa. Auto-detects seconds vs milliseconds and shows UTC, local and relative time (e.g. "5 minutes ago").

▸ UUID / GUID GENERATOR
Generate UUID v4 IDs for databases, API tests and mock data. Batch generation with uppercase and no-hyphen options.

▸ BASE64 ENCODER & DECODER
Encode and decode Base64 strings instantly — handy for API payloads, Basic Auth headers and embedded data.

▸ URL ENCODER & DECODER
Encode and decode URLs and query parameters for debugging query strings, deep links and redirects.

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PERFECT FOR
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• Android & mobile developers
• Backend & API engineers
• Web developers
• DevOps & SRE engineers
• QA testers & automation engineers
• Computer science students
• Anyone learning REST APIs, JSON or regex

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ALSO KNOWN AS
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Download Dev Toolkit now — the only developer tools app you'll need on Android. 100% free. No sign-up. Most tools work offline.

Have feedback or a tool request? Email us — we ship updates every month.