Diffactly

A free, fast, native macOS diff checker.

A fast, native and free macOS text comparison tool with real-time diff highlighting and a minimal interface.

Screenshots

Review a code change – side-by-side, with word- and character-level highlights inside edited lines.

Check a config change before you ship it – a unified view in light mode, like git diff but readable.

Compare document revisions – with the optional Insights panel: similarity, line composition, a clickable change map and word shifts.

Features

• Accurate diffs: lines are aligned with a weighted algorithm that favours long, meaningful matches (re-indented lines still line up), and edited lines are paired by similarity so you see what changed inside them
• Three precisions: Smart (word diff, refined to single letters for typo-sized edits), Word, and Character
• Moved-block detection, including blocks that were moved and edited, with the edits highlighted
• Edit, Split and Unified views: live highlighting while you type, or an aligned read-only comparison with collapsible unchanged lines and next/previous change navigation (⌃⌘↓ / ⌃⌘↑)
• Ignore options: whitespace, case, quote style, dash style and custom strings
• Transforms: lowercase, sort lines, join lines, trim whitespace
• Word counts: live word totals for both texts (with the net change) in the status bar, plus the words and characters in your selection while editing
• Insights (optional): toggle the chart button (⌥⌘I) for similarity, line composition, a clickable change map and word-frequency shifts
• Open files with ⌘O / ⇧⌘O, drag-and-drop, Finder's Open With, or diffactly --gui
• Auto, Dark and Light modes
• Native: SwiftUI + AppKit, no dependencies

⌨️ Command line

The same engine ships as a CLI (DiffactlyKit/, Swift package):

scripts/install-cli.sh            # builds and installs `diffactly`

diffactly old.txt new.txt             # coloured unified diff with inline highlights
diffactly -f split -l word a.md b.md  # side-by-side in the terminal
diffactly -f inline draft1 draft2     # [-removed-]{+added+} word diff
diffactly -s -g before.json after.json   # stats plus graphs (composition, change map, word shifts)
diffactly -f json a b                 # machine-readable result
diffactly -f patch a b | patch a      # valid unified patch
diffactly dirA dirB                   # compare folders recursively
diffactly --gui a b                   # open the comparison in Diffactly.app
git config --global diff.external "diffactly git"   # use Diffactly for `git diff`

Exit status follows diff: 0 same, 1 different, 2 trouble. Run diffactly --help for every option.

💻 Get it

Download the .app from the releases page, or build it yourself by opening Diffactly.xcodeproj in Xcode.

Found a bug? Please report it.

🤝 Contributing

We welcome contributions! Here's how you can help:

1. Clone the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

Please ensure your PR:

• Follows the existing code style
• Includes appropriate tests
• Updates documentation as needed

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

🔗 Links

• Repository: QuantumKuba/Diffactly
• Report issues: GitHub Issues