Free Online Developer Tools
All tools run entirely in your browser — no data leaves your device
JSON Formatter
Online JSON formatter, validator and compressor with syntax error highlighting
Base64 Encoder/Decoder
Online Base64 encoder and decoder, supports Unicode and UTF-8
URL Encoder/Decoder
Online URL encoder and decoder using encodeURIComponent and decodeURIComponent
Word Counter
Real-time character, word, line and paragraph counter with Chinese character support
Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and vice versa
UUID Generator
Batch generate UUID v4 online with one-click copy and uppercase option
Color Picker
Online color picker with real-time HEX, RGB and HSL conversion
Markdown Preview
Online Markdown editor with live preview — write on the left, preview on the right
Image Compressor
Compress images in your browser — no upload, fully private. Supports JPG, PNG and WebP
Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-512 hashes online for any text input
Regex Tester
Test regular expressions online with real-time match highlighting and full JS regex support
QR Code Generator
Generate high-quality QR codes from text or URLs with PNG download
Diff Checker
Compare two texts and find differences — like Git diff for plain text
IP Lookup
Look up IP address geolocation — country, city, ISP, and timezone info
JSON to CSV Converter
Convert JSON to CSV online with nested data flattening and CSV export
Online Timer
Online countdown timer and stopwatch — runs in background, never misses a beat
CSS Minifier
Minify CSS online — strip whitespace and comments to reduce file size
HTML Entity Encoder
Encode and decode HTML entities online — escape special characters and prevent XSS
PX to REM Converter
Convert PX to REM and REM to PX online with customizable root font size