DiffMill
Plain Text diff
Split or unified layout, smart word/character highlights, hide whitespace, syntax coloring for code and logs, and a change list for fast navigation.
Windows desktop · Local-first
DiffMill compares Word, Excel, PDF, plain text, and images on your PC. Plain-text diffs, rich previews, Word redlines, Excel grids, OCR for scanned PDFs, and pixel-accurate image modes— in one focused app.
Real UI from the Windows app—local compare, multiple views, no upload step.
Text is the source of truth. Visual views help you trust what changed.
Split or unified layout, smart word/character highlights, hide whitespace, syntax coloring for code and logs, and a change list for fast navigation.
Formatted preview aligned to diff rows. When Microsoft Word is available, open a true redline view with insertions and deletions styled like Track Changes.
Side-by-side worksheets with cell-level diffs, format-only changes, and export to CSV or HTML for sharing.
Text-layer PDFs diff like documents. Scanned PDFs can run OCR automatically and compare recognised text in a dedicated OCR Text view.
Compare photos and renders with Split, Fade, Flicker, Slider, Highlight, and Subtract modes—drag to pan and zoom without clutter.
Comparisons run locally. No account, no upload queue, no subscription required for core diff features on your machine.
Pick a comparison type from the home screen or open files from the command line.
Three steps from files to a reviewable diff.
Drop original and modified files, browse, or reopen a pair from Recent.
Press Compare or F5. Office formats use LibreOffice where needed; PDFs use the text layer or OCR.
Jump between changes, switch Plain / Rich / Grid / OCR tabs, and export HTML or PDF reports.
Your documents stay on your computer. DiffMill does not send file contents to our servers for comparison.
Download DiffMill, then purchase a license when you are ready. Checkout is handled by Creem.
One-time or subscription — see checkout for current price
DiffMill includes a 10-comparison trial. After checkout, enter your license key in the app under Preferences → License.
Install the latest build for Windows x64. Verify the SHA-256 checksum after download when provided on the release page.
64-bit · Windows 10 or later
Release packages are published in website/downloads/ for this site.
If a link is not yet available, build from source or check the project release notes.
The Windows app includes 10 free comparisons, then requires a license. Use the Creem checkout page or Preferences → License in the app. Payments are processed by Creem; DiffMill never sees your card number.
Yes. After installation, comparisons work offline except for optional update checks if you enable them in Preferences.
Online tools upload your files. DiffMill keeps originals and modified copies on your machine— suited to contracts, spreadsheets, and internal documents.
Yes. Run DiffMill.exe --cli original modified for text reports, plus other flags for redline, OCR, and image tests. See the developer documentation in the repository.
The current release targets Windows. The core app is built with Qt and may be ported later; watch this site for updates.