Free Developer Tools

100% client-side. Your data never leaves your browser.

🔒 Privacy First — No server processing, no data collection

All Tools

{ }

JSON Formatter

Beautify, minify, and validate JSON data. Handles large files with ease.

Popular
B64

Base64 Encode / Decode

Encode text to Base64 or decode Base64 strings. Supports image conversion.

Popular
%

URL Encode / Decode

Encode or decode URLs and query parameters instantly.
⇄

JSON ↔ CSV Converter

Convert JSON data to CSV for Excel, or CSV back to JSON format.

Popular
🔑

JWT Decoder

Decode and inspect JSON Web Tokens. View header, payload, and signature.
🕐

Unix Timestamp Converter

Convert between Unix timestamps and human-readable dates with timezone support.
🆔

UUID Generator

Generate random UUIDs (v4) instantly. Single or batch generation.
#️

Hash Generator

Generate MD5, SHA-1, SHA-256, SHA-512 hashes from any text input.
Aa

Lorem Ipsum Generator

Generate placeholder text in paragraphs, sentences, or words.
≠

Diff Checker

Compare two texts side by side and highlight differences.
🎨

Color Converter

Convert colors between HEX, RGB, HSL, and Tailwind CSS classes.
M↓

Markdown Preview

Write Markdown and see live preview. Export to HTML anytime.

Why DevToolKit?

🔒 100% Private

All processing happens in your browser. Your data is never sent to any server. No tracking, no cookies, no analytics.

⚡ Fast

No server round-trips. Everything runs locally using modern Web APIs and Web Workers for heavy processing.

📱 Works Offline

Once loaded, all tools work without internet. Add to home screen for instant access.

🆓 Always Free

No sign-up required. No usage limits. No premium tiers. Every tool is completely free.

🎯 Precise Error Location

Other tools only say "Invalid JSON". We tell you the exact line and column, with code context.

🌍 7 Languages

English, Chinese, Japanese, Korean, Spanish, Portuguese, French. Auto-detects browser language.

📁 File Upload

Upload files directly instead of copy-pasting large texts.