Code & developer tools
Format, minify, convert and inspect code — all locally.
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This is the largest category on the site: formatters and minifiers, converters between JSON, YAML, XML, CSV and TOML, generators that turn a JSON sample into typed models for TypeScript, Python, Go, Rust, PHP and more, regex and cron testers, diff viewers and encoders. The common thread is that every one of them runs entirely in the page. That is not a marketing line — it is the reason you can safely paste a real API response, a staging config or a production query into any of them.
Tools in this category
109 JSON Formatter & Validator Paste JSON to pretty-print it with your preferred indentation, validate syntax with precise error locations, or minify it to one line. CSS Minifier Compress your stylesheets by removing comments, whitespace and redundant syntax. See exact size savings before and after. HTML Minifier Shrink your HTML by removing comments and collapsing whitespace — safer page-speed wins with zero server round-trips. JavaScript Minifier Compress JavaScript by stripping comments and whitespace. Your code is processed locally and never uploaded anywhere. SQL Formatter & Beautifier Turn messy one-line queries into cleanly indented, readable SQL. Supports MySQL, PostgreSQL, SQLite, T-SQL, MariaDB and more. Regex Tester & Playground Write a pattern, paste test text and watch matches highlight live — with capture groups, flags and a quick syntax reference. Meta Tag Generator Fill in your page details and get complete, ready-to-paste HTML meta tags — SEO basics, Open Graph and Twitter Cards, with a live snippet preview. UUID / GUID Generator Generate one or hundreds of RFC-4122 UUID v4 identifiers with formatting options. Uses your browser’s native crypto — instant and offline-capable. JWT Decoder Paste a JSON Web Token to inspect its header and payload, check expiry with readable timestamps, and verify structure — entirely on your device. Text Diff Paste two versions of a text and see every added, removed and changed line highlighted instantly. Perfect for code review, contracts and content edits. CSS Gradient Generator Design linear, radial and conic gradients with draggable color stops and a live preview — then copy clean, ready-to-use CSS. Cron Expression Generator Compose cron schedules and understand existing ones in plain words. Code Beautifier Un-minify and re-indent HTML, CSS and JavaScript with one click. JSON to TypeScript Interfaces Generate clean TypeScript interfaces from any JSON sample. HTML to JSX Converter Turn any HTML snippet into valid React JSX in one click. JSON Path Finder Click any value in your JSON and copy its exact path. .gitignore Generator Ready-made ignore rules for every language and OS — combine freely. robots.txt Generator Compose allow/disallow rules and get a valid robots.txt instantly. Open Graph Preview See your link exactly as social networks will render it. JSON Diff & Compare Structural JSON comparison — see exactly what changed. XML Formatter & Validator Pretty-print and syntax-check XML instantly. JWT Generator (HS256) Build and sign test JWTs locally — secrets never leave your device. URL Slug Generator Clean, SEO-friendly slugs from any headline — instantly. Markdown Editor with Live Preview Write Markdown on the left, see rendered HTML on the right. String Escape / Unescape Escape strings safely for JSON, HTML, SQL, regex and more. HTML Entity Encoder & Decoder Encode special characters as HTML entities — or decode them back. Box Shadow Generator Craft the perfect CSS shadow with sliders and live preview. CSS Flexbox Playground Tweak flexbox properties visually and copy the CSS. CSS Grid Generator Design grid layouts visually — get clean CSS instantly. HTTP Status Codes Reference What every status code means — and how to fix it. URL Parser & Analyzer See and edit every component of a URL. Regex Explainer Token-by-token breakdown of any regex pattern. JSON to Go Struct Converter Generate Go structs with json tags from any JSON. cURL to Code Converter Turn cURL commands into fetch, Python, Node or PHP. package.json Generator A clean package.json from a simple form. API Mock Data Generator Realistic fake JSON records for testing APIs. PX to EM / REM Converter Pixel values to em, rem and % from any base size. Keyboard Tester Online Press any key — see code, key and modifiers live. JSON Schema Generator Infer a complete JSON Schema from sample data. Sample Data Generator Fake but realistic rows for testing, JSON or CSV. Cookie Consent Banner Generator GDPR banner snippet — HTML, CSS and JS in one copy. Markdown Table Generator Visual grid in, perfect Markdown table out. CSS to Tailwind Converter Map plain CSS rules to Tailwind utility classes. .env File Generator & Checker Write, validate and download clean .env files. GitHub Actions Workflow Generator CI YAML for your stack in one click. Conventional Commit Message Generator feat, fix, chore — well-formed commits every time. TypeScript to Zod Converter Turn TS interfaces into Zod schemas instantly. API Documentation Generator Turn endpoints into clean Markdown docs. Code Snippet Image Generator Beautiful shareable code screenshots as PNG. Visual SQL Query Builder Build SQL queries visually — no typing. Semantic Version (SemVer) Calculator Compare versions and test npm ranges. CSS Specificity Calculator Which selector wins? Get the (a,b,c) score. Makefile Generator Ready-made Makefiles with common targets. WebSocket Tester & Debugger Connect, send and inspect WS messages live. Codemod Runner Batch-transform code with pattern rules and preview the diff SQL to NoSQL Converter Translate SELECT/INSERT/UPDATE/DELETE into MongoDB or DynamoDB syntax GraphQL Playground Format, validate and inspect GraphQL queries without a server Dependency Analyzer Audit package.json dependencies, ranges and risk flags in seconds Set-Cookie Header Generator Build a secure Set-Cookie header with all attributes — plus matching JS and Express code. .editorconfig Generator Create a .editorconfig that keeps indentation and line endings consistent across every editor. tsconfig.json Generator Generate a modern, strict tsconfig.json with the right module resolution for your setup. Prettier Config Generator Click together your ideal .prettierrc.json — every option explained, output updates live. ESLint Config Generator Generate a modern ESLint flat config for TypeScript, React or Vue — install command included. Vite Config Generator Generate a vite.config.ts with the right plugin, proxy and alias setup for your framework. Webpack Config Generator Generate a working webpack.config.js with loaders, dev server and cache-busting output. Tailwind Config Generator Generate a tailwind.config.js with your brand colors, fonts, dark mode and plugins. PWA Manifest Generator Generate a complete web app manifest with icons and HTML tags — make your site installable. GitLab CI Pipeline Generator Generate a working .gitlab-ci.yml with stages, dependency caching and build artifacts. Open Source License Generator Generate a ready-to-commit LICENSE file — MIT, ISC, BSD, Apache, GPL or Unlicense. AI IDE Config Generator Generate CLAUDE.md, .cursorrules or Copilot instructions so your AI assistant follows your rules. MCP Server Config Generator Generate correct MCP server JSON for Claude, VS Code or Cursor — right wrapper, right path. curl Command Builder Compose complete curl commands with headers, auth and body — no syntax guessing. Git Command Generator Get the right Git commands for undoing, squashing, branching and tagging — safely. npm / yarn / pnpm / bun Converter See the equivalent command in all four package managers at once. Bash Script Generator Start from a battle-tested Bash template — strict mode, arg parsing, retries and more. Bash Formatter Re-indent messy shell scripts with consistent, readable block structure. GitHub README Generator Scaffold a professional README with badges, TOC and stack-specific install steps. README Badge Generator Create custom shields.io badges and grab ready-made GitHub badges in Markdown. Markdown TOC Generator Paste Markdown, get a GitHub-compatible linked table of contents instantly. Changelog Generator Turn your release notes into a clean Keep a Changelog entry with proper sections. Conventional Commit Generator Compose a valid Conventional Commit message with type, scope and footers. React Component Generator Scaffold typed React components, hooks, contexts and forms in one click. SQL CREATE TABLE Generator Define columns once, get correct CREATE TABLE DDL for four SQL dialects. SQL INSERT Generator Paste CSV data, get correctly quoted INSERT statements for your SQL dialect. JSON to SQL Converter Generate INSERT + CREATE TABLE statements from JSON JSON to HTML Table Render a JSON array as clean HTML table markup JSON to JavaScript Object Turn JSON into an idiomatic JS object literal JSON Stringify / Escape Text Escape text as a JSON string literal — and back CSV to SQL Converter Generate INSERT statements from CSV data CSV to HTML Table Render CSV data as clean HTML table markup XPath Tester Run XPath queries against XML instantly dotenv Linter Catch .env mistakes before they break your deploy JSON to C# Converter Turn JSON into ready-to-paste C# classes JSON to Java Converter Turn JSON into ready-to-paste Java classes JSON to Kotlin Converter Turn JSON into ready-to-paste Kotlin data classes JSON to Swift Converter Turn JSON into ready-to-paste Swift structs JSON to Rust Converter Turn JSON into ready-to-paste Rust structs JSON to Dart Converter Turn JSON into ready-to-paste Dart classes JSON to Python Converter Turn JSON into ready-to-paste Python data classes JSON to Pydantic Converter Turn JSON into ready-to-paste Pydantic models JSON to PHP Converter Turn JSON into ready-to-paste PHP classes JSON to Zod Converter Turn JSON into ready-to-paste Zod schema JSON to GraphQL Converter Turn JSON into ready-to-paste GraphQL schema JSON to Protobuf Converter Turn JSON into ready-to-paste Protobuf schema JSON to Mongoose Schema Generator Infer a ready-to-use Mongoose schema from sample JSON JSON to Prisma Schema Generator Turn sample JSON into a Prisma model in one click JSON Viewer Explore any JSON payload as a readable tree JSON Schema Validator Check any JSON document against its schema with Ajv NDJSON to JSON Converter Convert JSON Lines to a JSON array — and back
About these tools
Why local processing is the point for developers
The snippets developers most want to format are also the most sensitive: a response containing customer records, a config holding connection strings, a token pasted while debugging. Any online tool that posts your input to a server puts that text in someone else's logs. Here the payload stays in the tab, which means you can use these tools on real data instead of sanitising it first.
Formatting, minifying and validating
A formatter re-prints your code with consistent structure, and the reprint is also the fastest syntax check there is: if it will not format, it does not parse. A minifier goes the other way, stripping everything a machine does not need, which is what you want for anything shipped over the wire. Validators go further and tell you where the structure breaks rather than only that it does.
Generating types from a JSON sample
Hand-writing an interface for a large API response is tedious and easy to get subtly wrong — an optional field typed as required is a runtime error waiting for the one payload that omits it. Give the generator a representative sample and it infers the shape and produces a matching TypeScript interface, Python dataclass, Pydantic model, Go struct, Rust type, Zod schema or Prisma model.