Free Online Developer Tools
All tools run entirely in your browser — no data leaves your device
JSON FormatterHot
Online JSON formatter, validator and compressor with syntax error highlighting
Base64 Encoder/DecoderHot
Online Base64 encoder and decoder, supports Unicode and UTF-8
Unix Timestamp ConverterHot
Convert Unix timestamps to human-readable dates and vice versa
UUID GeneratorHot
Batch generate UUID v4 online with one-click copy and uppercase option
Markdown PreviewHot
Online Markdown editor with live preview — write on the left, preview on the right
Image CompressorHot
Compress images in your browser — no upload, fully private. Supports JPG, PNG and WebP
QR Code GeneratorHot
Generate high-quality QR codes from text or URLs with PNG download
Video TranscoderHot
Transcode videos in your browser — convert between WebM VP8/VP9 and MP4, powered by browser-native APIs
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
Color Picker
Online color picker with real-time HEX, RGB and HSL conversion
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
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
Password Generator
Generate cryptographically secure random passwords with customizable length and character sets
Base Converter
Convert numbers between binary, octal, decimal and hexadecimal bases online
Case Converter
Convert text between uppercase, lowercase, camelCase, snake_case, PascalCase and more
SQL Formatter
Format and beautify SQL queries online with proper indentation and keyword highlighting
Text Deduplicator
Remove duplicate lines from text online — keep first, keep last, or keep only unique lines
JWT Parser
Decode and inspect JWT tokens online — view header, payload, signature and verify expiration
YAML ↔ JSON Converter
Convert YAML to JSON and JSON to YAML online with real-time bidirectional conversion
Mermaid Chart Preview
Live Mermaid diagram editor — preview flowcharts, sequence diagrams, Gantt charts and more with SVG export
QR Code Decoder
Decode QR codes from images online — upload or drag & drop, fully private browser-side processing
Image to Base64
Convert images to Base64 data URIs online with adjustable compression quality
HTML to Markdown
Convert HTML to Markdown online — supports headings, bold, italic, links, images, lists, code blocks and more