Free Online Developer Tools
Free online developer tools to format, validate, minify, encode, decode and generate JSON, HTML, CSS, JavaScript, SQL, Base64, URLs, hashes, UUIDs and more.
38 tools shown
Base64 DecoderDecode Base64 data into readable Unicode text.
Base64 EncoderEncode Unicode text safely as Base64.
Binary to DecimalConvert a binary number to decimal.
Color Contrast CheckerCalculate WCAG contrast ratio and AA or AAA pass results for two colors.
CSS FormatterBeautify CSS rules with consistent indentation and line breaks.
CSS Gradient GeneratorDesign a two-color linear gradient with live preview and copyable CSS.
CSS MinifierRemove CSS comments and unnecessary spacing without changing quoted values.
Decimal to BinaryConvert a decimal integer to binary.
Hex to DecimalConvert a hexadecimal number to decimal.
HEX to RGB ConverterConvert hexadecimal colors into RGB values.
HTML DecoderConvert HTML entities back into characters.
HTML EncoderConvert HTML characters into safe entities.
HTML FormatterFormat HTML markup with readable line breaks and indentation.
HTML MinifierMinify HTML while preserving preformatted, textarea, script and style content.
JavaScript FormatterMake JavaScript easier to inspect with conservative indentation and line breaks.
JavaScript MinifierApply conservative browser-side JavaScript minification while preserving strings and template literals.
JSON FormatterFormat and beautify JSON with readable indentation.
JSON MinifierMinify JSON by removing unnecessary whitespace.
JSON ValidatorCheck JSON syntax and locate common errors.
JWT DecoderDecode JWT header and payload data locally without claiming signature verification.
Meta Tag GeneratorGenerate essential title, description, canonical, robots and Open Graph tags.
Online Code Editor & PlaygroundWrite HTML, CSS and JavaScript online with a live sandboxed preview, captured console, responsive device modes, templates, formatting, minifying and downloadable project files.
PX to REM ConverterConvert pixel values to rem units using an adjustable root font size.
Query String ParserConvert URL query parameters into readable JSON while preserving repeated keys.
Regex TesterTest a JavaScript regular expression, flags and sample text with detailed match results.
REM to PX ConverterConvert rem values to pixels using an adjustable root font size.
Robots.txt GeneratorCreate a simple robots.txt file with user-agent, allow, disallow and sitemap directives.
Schema Markup GeneratorGenerate structured JSON-LD for Article, FAQ, Breadcrumb, Organization, Local Business and Product schema types.
SHA-256 Hash GeneratorGenerate a SHA-256 hash locally with the Web Crypto API.
Slug GeneratorConvert a heading or phrase into a clean lowercase URL slug.
SQL FormatterFormat common SQL clauses into a more readable query layout.
Unix Timestamp ConverterConvert Unix timestamps to dates and dates back to timestamps.
URL DecoderDecode percent-encoded URL text.
URL EncoderEncode text for safe use inside a URL.
URL ParserBreak a URL into protocol, host, port, path, query parameters and fragment.
UUID GeneratorGenerate secure version 4 UUID values.
XML FormatterBeautify XML with clean indentation and validate its syntax.
XML MinifierMinify valid XML by removing unnecessary space between elements.
No matching tool found
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Fast browser tools for code and web work
Format, validate, minify, encode, decode and generate common development data with JSON, HTML, CSS, JavaScript, SQL, Base64, URL, JWT, UUID, hash, colour and regex utilities. Workbench layouts keep input, options and output readable on desktop and mobile.
How to choose the right tool
Treat generated or transformed code as a development aid. Test output in your own project, keep source files under version control and use a project-aware compiler, linter or security review before production deployment.