Free Online Tools

Collection of free, fast, browser-based tools for developers, designers, and daily use. No downloads, no sign-ups.

CoolTool is a growing collection of free, fast, and privacy-friendly online tools for developers, designers, and everyday tasks. Every tool runs entirely in your browser — your files and data never leave your device. No downloads, no sign-ups, and no limits.

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Developer Tools

13 tools

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Image Tools

1 tool

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Daily Tools

4 tools

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AI Tools

2 tools

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Life Tools

4 tools

Developer Tools

Developer utilities for everyday coding — encode and decode, format JSON, hash files, and debug right in your browser.

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Base64 Encode / Decode

Free online Base64 encoder and decoder. Encode text or files to Base64 format, or decode Base64 back to readable text.

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JSON Formatter & Validator

Format, validate, and prettify JSON data online. Parse JSON with syntax highlighting and error detection.

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Color Converter (HEX, RGB, HSL)

Convert colors between HEX, RGB, and HSL formats. Preview colors and get matching color schemes.

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Linux Timestamp Converter

Convert Unix timestamps to human-readable dates and vice versa. Supports batch conversion and timezone selection.

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URL Encoder & Decoder

Free online URL encoder and decoder. Instantly encode or decode URLs with encodeURIComponent and encodeURI modes.

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UUID Generator

Generate random UUIDs online with version support. Create UUID v1, v4, and v7 identifiers in multiple formats.

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MD5 & SHA Hash Generator

Generate MD5, SHA-1, SHA-256, SHA-384, SHA-512 hashes online. Hash text and files instantly in your browser.

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HTML Entity Encoder & Decoder

Free online HTML entity encoder/decoder. Encode or decode HTML entities instantly with named, decimal, and hex formats.

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Cron Expression

Free online cron expression generator. Convert cron expressions to human-readable format. Build cron expressions visually.

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JWT Decoder

Free online JWT decoder and debugger. Decode, inspect, and verify JWT tokens with support for multiple algorithms.

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Markdown Preview

Free online Markdown preview and WYSIWYG editor. Write Markdown with live preview, export to HTML.

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Text Diff Checker

Free online text diff checker. Compare text differences side by side, highlight additions and deletions instantly.

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Regex Tester

Free online regex tester. Test regular expressions with real-time matching, replacement, and code generation.

Image Tools

Optimize and compress images entirely in your browser — no server uploads, so your files stay private.

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Image Compressor

Compress PNG, JPEG, WebP, and AVIF images instantly in your browser — no upload to server needed.

Daily Tools

Everyday tools for writing, security, and media — count words, generate passwords, and create QR codes.

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Word Counter & Character Counter

Count words, characters, sentences, and paragraphs online. Free text analysis tool with readability score.

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QR Code Generator

Generate QR codes online for free. Create custom QR codes with colors, logos, and different error correction levels.

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Password Generator

Generate strong, secure passwords online. Customize length and character sets with cryptographically secure randomness.

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Case Converter

Free online case converter. Convert text to uppercase, lowercase, title case, camelCase, snake_case and more instantly.

AI Tools

AI-powered helpers that summarize text and translate between languages in seconds.

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AI Text Summarizer

Free AI-powered text summarizer. Summarize articles, documents, and text using AI technology.

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AI Translator

Free AI-powered translator. Translate text between 17+ languages using AI technology.

Life Tools

Practical calculators for health, dates, percentages, and unit conversions.

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Percentage Calculator

Free online percentage calculator. Calculate percentages, percentage change, percentage of a number, and reverse percentage.

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BMI Calculator

Free online BMI calculator. Calculate your Body Mass Index with WHO, Asian, and Child standards. Metric and imperial units.

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Date Calculator

Free online date calculator. Calculate date differences, add/subtract days, count workdays, and calculate age with zodiac & astrology.

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Unit Converter

Free online unit converter. Convert length, area, volume, mass, temperature, speed, and more with instant results.