Free Developer Tools
Everyday utilities for building and debugging software — validate JSON, decode a JWT, test a regex, diff two files and more. Every tool runs locally in your browser, so nothing you paste is ever uploaded.
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JSON Validator
Validate and pretty-print JSON in your browser. Nothing is uploaded — it all runs locally.
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Base64 Encoder / Decoder
Encode and decode Base64 text (UTF-8 safe) and Base64-encode any file, right in your browser. Nothing is uploaded.
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JWT Decoder
Decode, verify, and generate JSON Web Tokens in your browser. Inspect claims with human-readable hover dates, verify HS/RS/ES/PS signatures with a secret, PEM key, JWK, or JWKS, and sign new tokens. Nothing is uploaded.
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Regex Tester
Test regular expressions with live match highlighting and capture groups. Uses your browser's own regex engine — nothing is uploaded.
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Unix Timestamp Converter
Convert Unix timestamps to human dates and back, with live epoch time and timezone-aware output. Runs entirely in your browser.
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UUID Generator
Generate random UUID v4 identifiers in bulk, with uppercase and no-dashes options and one-click copy. Uses your browser's secure RNG — nothing is uploaded.
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Color Picker & Converter
Pick a colour and convert between HEX, RGB and HSL, with a built-in WCAG contrast checker. Runs entirely in your browser.
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CSS Gradient Generator
Create linear and radial CSS gradients visually: pick colours and stops, set the angle, preview live, and copy the CSS. Runs entirely in your browser.
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Number Base Converter
Convert numbers between binary, octal, decimal, hexadecimal and any base from 2 to 36. Arbitrary-precision, updates live, runs entirely in your browser.