Free developer tools & online compilers
Everyday developer utilities and online compilers that just work — run Python, SQL and HTML/CSS/JS right in your browser, format and validate JSON, encode and decode Base64, and generate hashes, UUIDs and cron expressions. The compilers execute real code (via WebAssembly and a sandboxed runner) and every formatter runs locally, so your code, tokens and payloads stay private. Free, no sign-up, no API key.
46 free developer tools · no sign-up required
Base64 Encode / Decode
Encode and decode Base64 text.
UUID Generator
Generate random UUID v4 identifiers.
Password Generator
Create strong, random passwords.
Hash Generator
SHA-256, SHA-1 and SHA-512 hashes.
QR Code Generator
Create QR codes for links and text.
SQL Formatter
Beautify and format SQL queries.
HTML Formatter
Format and indent HTML markup.
XML Formatter
Format, indent and tidy XML.
Markdown Previewer
Write Markdown, preview the HTML live.
Unix Timestamp Converter
Convert epoch timestamps to dates.
Cron Expression Generator
Build and explain cron schedules.
Color Palette Generator
Build palettes from any base color.
Barcode Generator
Create CODE128, EAN and UPC barcodes.
Favicon Generator
Generate favicons, ICO and a web manifest.
JWT Decoder
Decode and inspect a JWT instantly.
Regex Tester
Build and test regular expressions live.
URL Encoder / Decoder
Percent-encode and decode URLs.
HTML Entity Encoder / Decoder
Encode and decode HTML entities.
JSON to CSV Converter
Turn a JSON array into CSV.
CSV to JSON Converter
Convert CSV into JSON objects.
Excel Viewer
Open & view XLSX files online.
Excel to CSV Converter
Convert XLSX to CSV.
Excel to JSON Converter
Convert XLSX to JSON.
CSV to Excel Converter
Turn CSV into an XLSX file.
Excel to PDF Converter
Convert spreadsheets to PDF.
Number Base Converter
Binary, octal, decimal and hex.
Color Converter
HEX, RGB and HSL — instantly.
Text Diff Checker
Compare two texts line by line.
CSS Formatter & Minifier
Beautify or minify CSS.
Online Stopwatch
Start, stop and lap — in your browser.
Countdown Timer
Set a timer with an alarm.
Pomodoro Timer
25-minute focus, 5-minute breaks.
Random Number Generator
Random numbers in any range.
Random Picker
Pick a random name or shuffle a list.
Dice Roller
Roll virtual dice (d4–d100).
Wheel Spinner
Spin a wheel to pick a random winner.
Invoice Generator
Create and download a professional invoice.
Password Strength Checker
Test how strong a password is.
Roman Numeral Converter
Numbers to Roman numerals and back.
Binary Code Translator
Text to binary and binary to text.
HTML, CSS & JS Compiler
Online HTML, CSS & JS compiler with live preview.
Python Compiler
Online Python compiler — run Python in your browser.
JavaScript Compiler
Online JavaScript compiler & playground — run JS instantly.
TypeScript Compiler
Online TypeScript compiler — compile & run TS.
SQL Compiler (SQLite)
Online SQL compiler — run SQLite queries in your browser.
What Is My IP
Instantly see your public IP address.
Developer tools — frequently asked questions
How does an online compiler work?
An online compiler takes the code you type, runs it, and shows the output — with nothing to install. Some of ours run entirely in your browser using WebAssembly: Python via Pyodide (real CPython) and SQL via sql.js (real SQLite). Others send your code to a sandboxed runner that executes it and returns the result.
Which languages can I run in the browser?
You can run Python 3, SQL (SQLite) and front-end HTML, CSS and JavaScript directly in the browser, with a live preview for web code. There's also a quick code playground and an optional AI helper that can write or fix code for you.
Do these dev tools send my data to a server?
The formatters, encoders and generators run entirely client-side, so tokens, payloads and secrets you paste never leave your machine. The browser-based compilers (Python, SQL) also run locally; as a habit, avoid pasting real secrets or customer data into any online code runner.
Are the developer tools free?
Yes — completely free and unlimited with no account or API key required. The optional 'Ask AI' helpers use a small number of credits per request.
Can I use them offline?
Most dev tools and the WebAssembly compilers keep working after the page loads even without a connection, since the logic runs locally. Server-backed runners need a connection.