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Free Developer Tools

Six essential utilities for developers and designers, hosted at tool.zzml.com. Every tool runs 100% in your browser — no registration, no uploads, no tracking.

JSON Formatter & Validator

Format, beautify, minify, and validate JSON with real-time error highlighting and syntax checking. Paste messy JSON and get clean, indented output instantly.

Open JSON Formatter →

Unix Timestamp Converter

Convert Unix timestamps (seconds or milliseconds) to human-readable dates and back, with both UTC and local time. The tool every developer keeps open.

Open Timestamp Converter →

QR Code Generator

Generate high-quality QR codes from any text or URL. Customize the size and download as a PNG image instantly, all on your own device.

Open QR Generator →

Secure Password Generator

Create strong, random passwords with customizable length and character sets. Generated locally in your browser and never sent anywhere.

Open Password Generator →

Color Code Converter

Convert colors between HEX, RGB, and HSL formats with a live color preview and copy-to-clipboard support. Built for web designers.

Open Color Converter →

Text Character & Word Counter

Count characters, words, sentences, and paragraphs in real time. Perfect for essays, social media posts, and SEO meta descriptions.

Open Word Counter →
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Why Use Browser-Based Developer Tools?

Most developers have used cloud tool sites that ask for an account or upload your data to their servers. The tools on tool.zzml.com take a different approach: all processing happens locally in your browser with JavaScript, so your JSON, passwords, and text never leave your device.

That matters for real reasons. A password generator that sends output to a server is a security risk by definition. A JSON formatter that uploads your payload is uploading proprietary code or personal data. Running everything client-side removes those concerns entirely, and it also means the tools work even on flaky connections — once the page loads, the tool itself needs no internet.

What developers use most

All six tools are free, fast, and fully responsive, so they work just as well on a phone as on a workstation.