Format, beautify and validate JSON instantly in your browser with custom indentation.
JSON & Data
Free Online Developer Tools
This is the developer half of Mutqan Tools: the utilities you need while building and debugging software, grouped by what they work on. Format and convert JSON, encode and decode data, read HTTP headers and status codes, tidy SQL and code, decode tokens and compute hashes, and handle the small daily jobs — regex, UUIDs, timestamps, cron expressions, colors and number bases.
Every tool here runs entirely in your browser. Nothing you paste is uploaded, and each page explains what the tool does, how to use it and the questions people usually have about it.
Categories
Categories
JSON & Data Tools
Format, Validate, Convert & Diff JSON
20 toolsEncoding & Decoding Tools
Base64, URL, HTML, Hex & Binary
12 toolsWeb & HTTP Tools
Status Codes, Headers, CORS, cURL & OpenAPI
22 toolsSQL & Database Tools
Format, Validate & Generate SQL
8 toolsSecurity & Token Tools
JWT, Hashes, HMAC, Keys & Passwords
16 toolsCode & Text Formatting Tools
Beautify, Minify, Diff & Change Case
19 toolsDeveloper Utilities
Regex, UUID, Timestamps, Cron & Colors
24 toolsBy usage
All Developer tools Popular tools in this area
Decode JWT header and payload, inspect claims and check expiration — entirely in your browser.
Security
Validate JSON syntax and get precise error locations with helpful fix suggestions.
JSON & Data
Test regular expressions live with match highlighting, capture groups and replace preview.
Utilities
Encode text or files to Base64 (standard or URL-safe) in your browser.
Encoding
Decode Base64 or Base64url strings to text, with automatic padding repair.
Encoding
Convert timestamps (seconds, milliseconds, microseconds) to human dates and back, in any timezone.
Utilities
Generate UUID v4 (random) and v7 (time-ordered) identifiers in bulk, and validate existing ones.
Utilities
Guides
More guides Learn more
JSON & Data
What is JSON?
JSON explained in plain language: what it is, the six value types, the syntax rules that trip people up, how to format and validate it, and JSON vs XML/YAML.
EncodingWhat is Base64? Encoding Explained
Base64 explained: what it is and is not, how the encoding works, why output grows by a third, Base64 vs Base64URL, the = padding, and how to encode and decode.
WebHTTP Status Codes Explained
Every HTTP status code class explained with the codes you actually meet — 200, 301, 401, 403, 404, 422, 429, 500, 502, 503, 504 — causes and which to return.
DatabaseDatabase Testing for QA Engineers
How to test a database: CRUD checks through UI and API, constraints, referential integrity, consistency, test data, performance and security.
SecurityWhat is a JWT? JSON Web Tokens Explained
JWT explained simply: the three parts of a JSON Web Token, claims like exp and sub, how to decode and verify one, why decoding is not verifying, and security.
PerformancePerformance & Security Resilience Testing
How to test a product under load, failure and attack: load, stress and soak tests with real targets, failure injection, the OWASP baseline and what to record.
UtilitiesRegular Expressions (Regex) for Beginners
Learn regex from scratch: character classes, quantifiers, anchors, groups and flags, copy-ready patterns for emails, phones and dates, and how to test safely.
UtilitiesCron Expressions Explained
Cron expressions explained field by field: minute, hour, day, month, weekday, the *, /, - and , operators, common schedules, time zones and classic mistakes.
UtilitiesWhat is a UUID? v4 vs v7, UUID vs GUID & ULID
UUIDs explained: the 128-bit format, v4 vs v7, why v7 is better for database keys, UUID vs GUID vs ULID, collision odds, and how to generate and validate them.