Free developer tools

Format, validate and convert code and data in your browser: JSON, YAML, XML, SQL, HTML, CSS, JavaScript, Markdown, Base64, JWT, hashes, UUIDs and regular expressions. Nothing you paste is uploaded.

Online Compilers

Online Python Compiler Free online Python compiler: write and run Python 3.12 code in your browser with input(), the standard library and auto-loaded packages like NumPy and pandas.
Online JavaScript Compiler Free online JavaScript compiler and playground: run modern JS with async/await and see console output instantly, sandboxed in your browser.
Online TypeScript Compiler Free online TypeScript compiler: transpile TypeScript 5.6 to JavaScript, see the generated code and run it instantly in your browser.
Online PHP Compiler Free online PHP compiler: run PHP 8 code with a real PHP interpreter compiled to WebAssembly. Test functions, arrays, JSON and string handling instantly.
Online Ruby Compiler Free online Ruby compiler: run Ruby 3.3 code with the standard library using the official ruby.wasm build, right in your browser.
Online Lua Compiler Free online Lua compiler: run Lua 5.4 scripts instantly with a WebAssembly build of the official interpreter. Perfect for learning and testing.
Online SQL Compiler Free online SQL compiler: create tables, insert data and run SQL queries against a real SQLite database in your browser, with results as tables.
Online C Compiler Free online C compiler: write, compile and run C programs with a real Clang compiler running in your browser, with stdin input and warnings.
Online C++ Compiler Free online C++ compiler: compile and run C++20 programs with Clang in your browser, including the STL, iostream and stdin input. No sign-up.
Online R Compiler Free online R compiler: run R code with webR in your browser, including data frames, statistics, linear models and base graphics plots.
Online Prolog Compiler Free online Prolog compiler: run SWI-Prolog programs in your browser with facts, rules, recursion and formatted output. Nothing is uploaded.
Online Scheme Interpreter Free online Scheme interpreter: run Scheme and Lisp-style code with recursion, lambdas, lists and tail calls directly in your browser.
Online Clojure Compiler Free online Clojure compiler: run Clojure code with maps, vectors, lazy sequences and threading macros in your browser via the Small Clojure Interpreter.
Online CoffeeScript Compiler Free online CoffeeScript compiler: compile CoffeeScript 2 to JavaScript, view the generated code and run it instantly in your browser.

Formatters & Validators

JSON Formatter & Validator Free online JSON formatter and validator: beautify or minify JSON, find syntax errors with line numbers, sort keys and convert to YAML or CSV. Runs in your browser.
YAML Formatter & Validator Validate and format YAML online: catch indentation and syntax errors with line numbers, normalise formatting and convert YAML to JSON. Private, in-browser.
XML Formatter & Validator Free XML formatter: pretty-print or minify XML, check that it is well-formed and pinpoint errors. Works with SOAP, RSS, sitemaps and config files, in your browser.
SQL Formatter Format SQL queries online: beautify messy SQL with consistent indentation and keyword case for MySQL, PostgreSQL, SQL Server, SQLite, BigQuery and more.
HTML Formatter Free HTML formatter and beautifier: indent messy or minified HTML so it is readable, or minify it to save bytes. Runs entirely in your browser.
CSS Formatter & Minifier Format and minify CSS online: beautify compressed stylesheets for editing or minify CSS for production, with size savings shown instantly.
JavaScript Formatter & Minifier JavaScript beautifier and minifier: format minified JS so you can read it, or compress code with Terser for production. Private, client-side processing.
Markdown Editor & Preview Online Markdown editor with live preview: write GitHub-flavoured Markdown, see the rendered result instantly and copy the generated HTML.

Converters & Encoders

JSON ↔ YAML Converter Convert JSON to YAML or YAML to JSON instantly. Ideal for Kubernetes manifests, Docker Compose, CI pipelines and OpenAPI specs. Runs in your browser.
CSV ↔ JSON Converter Convert CSV to JSON or JSON to CSV online, with automatic delimiter detection, header rows and type conversion. Your data never leaves your browser.
Base64 Encode & Decode Base64 encoder and decoder: convert text to Base64 and back with full UTF-8 support, plus URL-safe Base64 for JWTs and data URIs.
URL Encode & Decode URL encoder and decoder: percent-encode query strings and path segments or decode encoded URLs, with component and full-URL modes.
Unix Timestamp Converter Unix timestamp converter: turn epoch seconds or milliseconds into human-readable dates in UTC and your time zone, or convert a date to a timestamp.

Developer Utilities

JWT Decoder Decode JSON Web Tokens online: view the header and payload, check expiry and issued-at times, and understand each claim. Tokens never leave your browser.
Password Generator Free strong password generator: create random passwords up to 128 characters with letters, numbers and symbols, see their strength, and generate in bulk. Nothing leaves your browser.
Hash Generator Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text instantly in your browser, and compare a hash against an expected value.
UUID Generator Generate UUIDs online: random version 4 or time-ordered version 7 UUIDs/GUIDs, one or in bulk, with uppercase and no-hyphen options.
Regex Tester Online regex tester for JavaScript regular expressions: see matches and capture groups highlighted live, try flags and test replacements.

Private by design

Every developer tool on this page runs entirely in your browser using JavaScript. The JSON, SQL, tokens or text you paste are processed on your own device and are never sent to our servers or stored, so they are safe for configuration files, logs and API responses. Your last input is remembered only in your own browser's local storage for convenience, and you can clear it at any time.

Why use online formatters?

Minified or machine-generated data is hard to read. A formatter adds consistent indentation and line breaks so you can spot structure and errors quickly, while a validator tells you exactly where a syntax problem is. Converters save time when moving between formats, for example turning a JSON API response into YAML for a Kubernetes manifest, or a CSV export into JSON for a script.

Working on networks too? Try our IP, DNS and network tools, from DNS lookup to the HTTP headers checker.

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