Redlinr
Visual Redline · 100% On-Device
Compare two documents.
See exactly what changed.
Drop an Original and a Revised document and Redlinr shows exactly what changed — deletions struck through in rose, insertions underlined in green — with an aligned split view and a plain-English summary. Nothing is uploaded: leases, offers and contracts never touch a web diff tool.
v1.4.0 · macOS 14+, including 27 Golden Gate · Apple Silicon & Intel · Signed & notarized by Apple · No account
How it works
Drop it in. See what changed. Export it.
Drop in Original & Revised
Two labeled drop zones — Original and Revised — collapse into a compact header once both documents are loaded. Word, PDF, RTF, ODT, HTML, Markdown or plain text, in any combination.
Redlinr compares
Paragraphs are aligned first, then a word-level diff runs only inside changed paragraphs — so even a 50-page document stays fast. Everything happens locally; nothing is uploaded.
Review the redline
Inline strikethrough and underline, an aligned split view, a "Change N of M" pager, moved-paragraph badges, and a plain-English headline with before→after value chips.
Export the redline
Save the redline as a single, self-contained HTML file to share — your Original and Revised documents are never modified, moved, or deleted.
What you get when you export — one HTML file, viewable in any browser, no Redlinr required.
One button swaps red and green for blue and amber — chosen by simulating red-blind, green-blind and blue-blind vision, and carried into the file you export.
Features
Everything you need to see what actually changed.
One focused, native window that turns two documents into a clear redline — without ever sending either one to the cloud.
Edit either side, and watch the diff move
Click any paragraph in the split view and type. The redline, the word counts and the change list all update as you type — so you can fix a typo, try alternative wording, or settle a clause without going back to Word and comparing again. The Original column stays locked until you say otherwise, because the baseline is the one thing you don't want to change by accident. Your files on disk are never rewritten; save the edited text as a new file when you're happy with it.
New in 1.2
Colors you can tell apart
Red and green is the one pair of colors roughly one man in twelve cannot separate — and it is the pair a redline leans on hardest. One button switches the whole comparison, and the file you export, to blue for additions and amber for deletions, with moves in a plain gray. Every color was checked against simulated red-blind, green-blind and blue-blind vision, so the fix for one kind of color blindness doesn't create another. Strikethrough and underline mark every change either way — color is never the only cue.
New in 1.3
Redline, and an aligned split view
Deletions struck through, insertions underlined, right inline — in rose and green, or the color-blind-friendly blue and amber. Toggle to an aligned side-by-side split view of Original vs Revised when you'd rather read them in full.
Inline · Split
A two-level diff that stays fast
Paragraphs are aligned first with a sequence matcher, then a word-level diff runs only inside changed paragraphs — so even large documents stay responsive. A single very long changed line falls back to a clean delete+insert instead of freezing the compare.
Performance
Change navigation pager
A floating "Change N of M" pager, with keyboard shortcuts, steps through every change one at a time — with a persistent highlight that follows along in the redline, the split view, and the sidebar.
Change N of M
Moved blocks, recognized
A paragraph that was relocated — not re-worded — is shown once with a "Moved" badge, instead of reading as a confusing deletion paired with an unrelated insertion.
Moved
Plain-English headline
A summary sentence surfaces the most significant changes at a glance, with paired before→after value chips for numbers, money, dates and percentages — the stuff you actually care about first.
Value chips
Ignore case & whitespace
Two toggles re-run the compare with relaxed matching, so a re-wrapped paragraph or a capitalization tweak doesn't drown out the changes that matter — while the rendered text always shows exactly what's in the document.
Automatic reload
Redlinr notices when an open document changes on disk — say, a lease you just re-exported — and offers a one-click reload, via a banner, a header button, or ⌘R. Done with this pair? Start over clears both sides at once — the trash icon beside Reload, or ⇧⌘K — and asks first if you have edits typed into either column.
⌘R · ⇧⌘K
Change summary sidebar
Words added and removed, and a clickable list of every change that jumps you straight to it in the redline — a fast way to triage a long document before you read it top to bottom.
Export the redline — or just the list
Save the redline as a single, self-contained HTML file — easy to email, archive, or hand to someone who doesn't have Redlinr installed. Or save just the change list, as plain text, Markdown or CSV, which is what you actually paste into an email about a contract or open in Numbers. Every export is written in the language you have Redlinr set to — headings, word counts, the "Moved" badge and all — and the HTML file declares that language for screen readers. Your Original and Revised files are never touched.
Self-contained
Every common document format
Word (.docx/.doc), PDF, RTF, ODT, HTML, Markdown and plain text — mix and match either side. Word/RTF/ODT/HTML go through macOS's
7 formats
textutil; PDFs read their text layer via PDFKit. A scanned, image-only PDF has no text layer — Redlinr offers to read it instead.Reads scanned PDFs
Drop in a scan and Redlinr offers to read it with your Mac's own text recognition — no upload, no OCR service, no extra download. It shows you which page it's on and you can stop it at any time. The result is labeled as recognized text, because that isn't the same thing as the document's own words.
On-device OCR
Find the change you care about
A fifty-page contract can have a hundred changes. Search the change list for a word — accents optional, so
Search & sort
cafe finds Café and lodz finds Łódź — narrow it to just the insertions, deletions, rewordings, moves or the changes that touched a number, date or amount, and sort by where it sits in the document, by type, by how much text it moved, or by the wording of the change itself. That last column sorts in the language you have Redlinr set to, so an accented word lands where you would look for it rather than past Z. The pager and keyboard shortcuts follow whatever you've narrowed to.100% on your Mac
No document — and no text from it — ever leaves your computer. No account, no cloud, no telemetry. Web-based diff tools make you upload private files to someone else's server; Redlinr never does. The only network calls are the optional license check and update check.
Privacy
Signed & notarized
Opens with a normal double-click — no "unidentified developer" warning, no Open Anyway, no Terminal. Signed with an Apple Developer ID and notarized by Apple.
No warnings
Built for everyone
Full keyboard shortcuts for navigating changes and reloading with ⌘R, light and dark mode that follows your Mac automatically (or pin one from the appearance toggle), and WCAG 2.1 AA accessibility throughout — zero serious or critical axe-core violations in either color scheme.
WCAG 2.1 AA
Speaks your language
Redlinr's interface comes in 13 languages — German, English, Spanish, French, Italian, Japanese, Korean, Dutch, Polish, Brazilian Portuguese, Russian, Turkish and Simplified Chinese — and auto-detects your Mac's language on first launch; switch anytime from the in-app flag picker. What you export is written in that language too. Dark and light mode both, following macOS or pinned from the appearance toggle.
13 languages · dark & light
Compares
DOCX
DOC
PDF
RTF
ODT
HTML
Markdown
Plain text
Pricing
Free for you. Fair for work.
Personal use is free forever — every format, unlimited comparisons, no key, no account, no watermarks. If Redlinr earns its keep at your job, a one-time business license keeps it supported.
Personal
Free forever
For individuals and personal projects
- Compare unlimited documents, every supported format
- Read-only comparison — your originals are never modified
- Inline redline, split view, and plain-English summary
- 100% on-device — nothing uploaded
- No account, no nag screens
- Free updates forever
Business
$5 / computer
One-time payment — no subscription
- Everything in Personal
- Use commercially at work
- One-time payment — no subscription
- Free updates forever
- Supports solo indie development
The personal tier is the full app — buy a business license only if you use Redlinr commercially. One seat per computer, paid once, yours for life. Secure checkout via Stripe; your license key is emailed instantly.
Download & install
Get set up in seconds.
Download the app and drag it into Applications — that's it. No Terminal, no Homebrew, no sign-up.
Version 1.4.0 · Released August 18, 2026 · Free updates forever
macOS 14 Sonoma or later, including macOS 27 Golden Gate · Apple Silicon or Intel
Everything Redlinr needs is built right into the app — no Python to install, no Homebrew, nothing else to set up. One universal build runs natively on Apple Silicon and Intel.
Opens with a double-click
Redlinr is signed with an Apple Developer ID and notarized by Apple, so it opens cleanly the first time — no
Open Anyway trip through System Settings, no Terminal. Open the DMG, drag Redlinr into Applications, and launch it.Check the file you downloaded
Redlinr is signed with an Apple Developer ID and notarized by Apple, and macOS checks that every time you open it — that is the check that catches a file altered on its way to you. To confirm it yourself, compare the SHA-256 of your copy with the one published for the
Redlinr.dmg this page serves.SHA-256 checksum
Published checksum
Run this on your download and compare
shasum -a 256 ~/Downloads/Redlinr.dmg
Or have your Mac compare them for you: save Redlinr.dmg.sha256 beside the download and run shasum -a 256 -c Redlinr.dmg.sha256.
FAQ
Common questions.
Is Redlinr really free?
Personal use is free forever — every supported format, unlimited comparisons, no account, no trial timer, no watermarks. If you use Redlinr at work, a one-time $5 business license per computer keeps it supported.
What file formats does it support?
Word (.docx and the legacy .doc), PDF, RTF, ODT, HTML, Markdown, and plain text — in any combination, so you can compare a .docx against a PDF export of the same document. Word, RTF, ODT and HTML are read through macOS's built-in textutil; PDFs are read through PDFKit's text layer.
Does Redlinr upload my documents anywhere?
No. Every compare runs entirely on your Mac — no document, and no text from it, ever leaves your computer. There is no account and no telemetry. The only times Redlinr contacts our server are to validate a business license key or to check for updates, which sends only the app version.
Will Redlinr change my original files?
No. Comparing is read-only — Redlinr never modifies, moves, or deletes either the Original or the Revised file. The only file it ever writes is one you explicitly ask for: Export, which saves the redline as a new, self-contained HTML file.
What happens with scanned or image-only PDFs?
Redlinr reads a PDF's text layer through PDFKit. A scanned, image-only PDF has no text layer, so Redlinr offers to read the pages with your Mac's own text recognition instead — on your computer, with nothing uploaded and no OCR service involved. It shows which page it is on and can be stopped at any point, and it labels the result as recognized text, because recognition makes mistakes that a document's own text layer does not.
Will macOS warn me about an unidentified developer?
No. Redlinr is signed with an Apple Developer ID and notarized by Apple, so it opens with a normal double-click the first time — no Open Anyway trip through System Settings, no Terminal.
How do I update Redlinr?
Redlinr updates itself. It checks about once a week and, when a new version is out, shows you what changed and offers to install it in place — the download is signature-checked, and one that doesn't verify is refused. You can also check on demand, turn the automatic check off in the update panel, or download the DMG from this page and drag it into Applications yourself. Your settings carry over.
Is there a Windows version?
Not yet — Redlinr is Mac-only for now, built around macOS's own textutil and PDFKit frameworks rather than a bundled cross-platform document engine.
I'm red-green color blind — can I use Redlinr?
Yes. One button in the toolbar switches the redline out of red and green and into blue for additions and amber for deletions, with moved paragraphs in a plain gray — in the inline view, the split view, the change list and the HTML file you export. The colors were chosen by simulating protanopia, deuteranopia and tritanopia and measuring how far apart each pair stays, so the fix for red-green blindness does not create a blue-yellow one, and additions are darker than deletions so the two survive a black-and-white printout. In both palettes deletions are struck through and insertions underlined, so color is never the only thing marking a change.
What about paragraphs that just moved, or differences in case and whitespace?
A paragraph that was relocated rather than reworded is shown once with a "Moved" badge, instead of reading as a confusing delete-and-insert pair. Separate Ignore case and Ignore whitespace toggles re-run the compare with relaxed matching so formatting-only differences don't drown out real changes — the text on screen always shows what's actually in the document.
How do I navigate a long document's changes?
A floating "Change N of M" pager, with keyboard shortcuts, steps through every change one at a time, with a persistent highlight that follows along in the inline redline, the split view, and the change summary sidebar.
How does the business license work?
A Business License is $5, one-time, per computer — no subscription. Buy it from the Pricing section above; checkout is handled securely by Stripe and your license key is emailed instantly. Enter it in Redlinr's License screen to activate.