About DiffPeek

A privacy-first diff tool built for developers and everyone else.

What is DiffPeek?

DiffPeek is a free online diff checker that lets you compare two versions of text, code, JSON, XML, CSV, HTML, files, and entire folders — right in your browser. Everything runs locally: no sign-up, no file uploads, no data tracking beyond anonymous usage analytics.

The name comes from "peeking" at diffs — getting a quick, clear view of what changed without the overhead of installing software or handing your data to a server.

Why we built it

Most diff tools online either upload your files to their servers, require a paid account for folder comparison, or show intrusive ads that make a focused task frustrating. DiffPeek was built to fix all three problems at once.

It uses the browser's native File System Access API and standard diff algorithms (Myers LCS) implemented entirely in JavaScript — the same approach used in tools like Git and VS Code, but accessible directly in a browser tab.

Key features

• Folder diff — compare two entire directories and see every added, deleted, and modified file with full side-by-side diffs
• Text, code, JSON, XML, CSV, HTML compare — paste any content and get an instant GitHub-style diff
• Character-level highlighting — see exactly which characters changed within a modified line
• 100% private — your files never leave your device
• No account needed — open the page and start comparing

Privacy commitment

All diff operations run in your browser using JavaScript. We cannot see your files, text, or code. We collect only anonymous, aggregated analytics (page views, browser type) via Google Analytics to understand usage patterns and improve the product. See our Privacy Policy for details.

Contact

Have a feature request, found a bug, or want to get in touch? Email us at hello@diffpeek.com.