Best Free Online Developer Tools
Most day-to-day dev tasks share one shape: paste something in, get a result back. This collection gathers twenty-five developer utilities people reach for constantly — every one runs locally in your browser, so nothing you paste ever leaves the page.
JSON Formatter
Prettify, minify and validate JSON in one paste.
Base64 Converter
Encode or decode text and files locally.
URL Encoder
URL-encode or decode single strings or batches.
JWT Decoder
Inspect JWT segments locally with expiry status.
SQL Formatter
Beautify or minify SQL across five dialects.
Hash Generator
MD5/SHA checksums for text and files.
Regex Generator
Describe a match, get a regex with a tester.
Unix Timestamp Converter
Unix timestamp ↔ human time, ms included.
UUID Generator
Bulk UUID v4 and time-ordered v7, multiple formats.
Password Generator
Crypto-strong passwords, tunable sets and length.
Random Number Generator
Unbiased picks in any range, unique mode included.
Binary Converter
Text↔binary/hex/octal plus BigInt base math.
px to rem Converter
px/rem/em conversion with bulk CSS rewrite.
Markdown Editor
Markdown editor with live preview.
Meta Tag Generator
Copy-ready <head> meta, OG and Twitter tags.
robots.txt Generator
Visual crawl rules, presets and templates.
RGB to Hex Converter
Convert between RGB and HEX color values.
cURL to Code Converter
Turn a curl command into ready code in many languages.
IP Address Lookup
Look up any IP for location, ISP and timezone.
Mermaid Diagram Editor
Mermaid syntax to live diagrams, exported as SVG.
HTML Runner
Sandboxed HTML/CSS/JS playground with download.
SVG Previewer
Paste or upload SVG, preview and export PNG.
Markdown Mind Map
Markdown outline to interactive mind map.
Password Manager
Local browser vault plus password generator.
WiFi Password Generator
Strong WiFi passwords with entropy meter.
ASCII Art Generator
Image to ASCII art with code-comment formats.