DiffAI
Professional
redlines, in
seconds.
Compare versions of DOCX, PDF and Excel files and get a faithful redline PDF — processed 100% locally on your Mac or Windows machine.
Built for people who
review contracts daily.
A faithful redline, not a reformatted one
Deletions struck through, insertions underlined, the original layout preserved — the output you'd expect from Word Compare, without the setup.
Signal vs. noise
Content changes are separated from dates, version stamps and formatting. You review what actually matters.
DOCX, PDF & Excel
Contracts, policies and cap tables in the same flow. Batch entire folders with automatic pairing.
100% local
Documents never leave your computer. Only license activation talks to the internet — everything else stays on your machine.
Every change,
classified and counted.
The engine doesn't just diff text — it classifies each change the way a reviewer would, and totals them in the Summary of Changes.
New language, underlined in blue
Every word added to the new version is marked inline, exactly where it entered the document — clauses, definitions, schedules, tables.
Removed text, struck through in red
Nothing silently disappears. Text removed from the base version stays visible, struck through, so you can judge what the other side took out.
Relocated blocks, tracked in green
When a clause travels to a different section, it isn't a delete plus an insert — it's flagged as moved, with origin and destination.
Style changes, highlighted — never noise
Bold, italics, and casing changes are highlighted separately from content, so a reformatted paragraph never masquerades as a rewrite.
From two versions to a
clean redline in four steps.
Drop
Drag both versions in — DOCX, PDF or Excel. Batch a whole folder and pairs are matched automatically.
Compare
The engine aligns clauses, tables and definitions, separating real changes from dates, versions and formatting noise.
Review
Read the redline the way you would in Word: insertions underlined, deletions struck through, moves in green.
Share
Export a faithful PDF, an editable DOCX, or an executive summary the client can read in one page.
Your documents never
leave your computer.
Comparison runs entirely on your machine. The only network call is license activation — the same endpoint the Account page uses to manage devices.
Local processing
No document, clause or metadata is ever uploaded
Offline after activation
Compare with the network cable unplugged if you like
Your outputs, your disk
Redlines and reports are written to a folder you choose
Simple. No surprises.
The trial starts automatically in the app. Subscribing sends your license key by e-mail — activate it on Mac or Windows, and manage devices in Account.
Try everything, no card
- Every Pro feature
- Up to 25 comparisons
- Batches of up to 5 pairs
- No credit card required
For daily contract review
- Unlimited comparisons
- Faithful redline PDF + editable DOCX
- HTML, Excel and JSON reports
- Unlimited batches
- 2 devices per license
For legal teams
- Everything in Pro
- 5 devices per license
- Your firm's brand on the PDFs
- Priority support
Questions? vendas@diffai.app
Download
Install on Mac or Windows.
The app runs locally. The internet is only used to activate your license and manage devices in Account.
Apple Silicon / Intel
Download the .zip, open it and drag DiffAI.app into Applications. If macOS says the app is damaged, run in Terminal: xattr -cr /Applications/DiffAI.app
Download .zipNote: For redline PDFs that keep the original DOCX layout, also install LibreOffice (free). Without it, the PDF uses a simplified layout; the editable DOCX redline still preserves formatting. The app will prompt you after install.
Download LibreOfficeWindows 10 / 11
Download the .zip, extract it and run diffAI.exe. Windows 10/11 with WebView2 (usually preinstalled).
Download .zip
Ready to compare
for real.
Download DiffAI, run the trial, and subscribe when you need unlimited comparisons.