About Diffspot

Diffspot is a free diff checker that never sees your data.

Most online comparison tools ask you to paste contracts, source code or customer spreadsheets into a website and trust that it handles them well. Diffspot takes a different approach: the comparison engine is downloaded to your browser and runs there, so there's nothing to trust. Your content never leaves your device.

Principles

• Private by construction. No uploads, no accounts, no stored comparisons. Ads are walled off in isolated frames.
• Fast. The engine is written in Rust and compiled to WebAssembly. It runs in a background thread, and the viewer draws only what's on screen.
• Complete and free. Every feature is free: merging, word-level changes, moved-block detection, ignore rules, exports, and comparisons of documents, spreadsheets, images and folders.
• Built for reading. Unchanged lines fold away, changes are easy to step through, and three views (side by side, unified and redline) suit code and prose alike.

What's inside

The diff engine builds on the open-source imara-diff and similar Rust crates. Syntax highlighting and language detection are Diffspot's own. PDF text is extracted with Mozilla's pdf.js, and spreadsheets are read with calamine. Read how Diffspot works for details.