Compare Word Documents Online — Free & Private
Drop two .docx files and see every change highlighted instantly. SnapTextCompare extracts text from Word documents locally with mammoth.js — no Microsoft Word, no signup, no upload. Built for legal, HR and editorial teams that can't ship confidential contracts to a third-party server.
No comparison yet. Paste or upload text in both fields below — results appear here automatically, and nothing is calculated until you do.
Compare your two texts
Original Text (A)0 words
Modified Text (B)0 words
Why Compare Word Documents in the Browser?
Word's built-in Compare is great — if you have Word, a license, and your team uses the same version. The moment a teammate is on a Mac without Office, a Chromebook, or just wants to spot-check a clause on their phone, that workflow breaks.
SnapTextCompare extracts DOCX body text with mammoth.js and compares it locally. This supports wording review, not a complete legal redline or a compliance determination. Review omitted document components and your organization's requirements separately; clear local History on shared devices.
What's Actually Inside a .docx File
A .docx file is a ZIP archive of XML files following the Office Open XML (ECMA-376) standard. The main content lives in word/document.xml; styles are in word/styles.xml; images and embedded objects sit in word/media/. Word's text is fragmented across hundreds of <w:r> ("run") elements wrapped in <w:p> ("paragraph") elements — runs split whenever formatting changes, even mid-word.
That's why naïvely concatenating XML text gives garbled output. Mammoth.js walks the document tree, joins adjacent runs intelligently, collapses formatting noise, and emits clean reading-order text — which is exactly what a textual diff needs. SnapTextCompare does the same in your browser tab and then runs the diff on the cleaned output.
Word Document Comparison Use Cases
Legal redlines. Verify counterparty's revised contract only touched negotiated terms — without sending a privileged draft through a third-party server.
HR policy updates. Diff successive versions of an employee handbook for a clean change log to attach to the company-wide announcement.
Academic revisions. Track supervisor edits between thesis drafts. Especially useful when "Track Changes" was disabled and you only have two clean files.
Editorial review. Show authors exactly what changed in their submitted manuscript before publication.
Cross-device review. Compare on a Mac, Chromebook, iPad or Linux box — no Word install, no Office 365 subscription.
Translation revisions. Compare two revisions in the same language to locate edits. Text comparison does not validate a translation's meaning.
SnapTextCompare vs Word's Compare Feature
| Feature | SnapTextCompare | Microsoft Word Compare |
|---|---|---|
| Cost | Free | Licensed desktop Word |
| Works on Mac / Linux / Chromebook | ✅ any browser | Word required |
| 100% in-browser | ✅ | N/A (desktop app) |
| Word-level highlighting | ✅ | ✅ |
| Preserves formatting | Text only | ✅ |
| Privacy (no upload) | ✅ | ✅ (local file) |
| Mobile-friendly | ✅ | Limited |
| Mixed format (.docx vs .pdf) | Extracted text | Requires import/conversion; behavior varies |
Best-Practice Workflow for Legal & HR Teams
1. Save both versions as .docx. If your counterparty sent a PDF, convert it first — diffing the same format gives the cleanest output.
2. Accept all tracked changes in the revised file before comparing. SnapTextCompare reads the resulting text, not the revision marks themselves, so accepting first gives a true "before vs after" view.
3. Run the diff in word mode. Legal language hinges on individual words — "shall" vs "may", "and" vs "or" — and word mode catches these instantly.
4. Export the result as HTML and attach to the matter file or email chain. Internal audit teams love a permanent change record.
5. For final sign-off, still open both files in Word side-by-side to confirm formatting (margins, headers, signatures) match. SnapTextCompare handles content; Word handles visual layout.
Limitations
Formatting: SnapTextCompare diffs text content, not visual formatting like bold/italic or paragraph styling.
Embedded objects: Tables become tab-separated text; embedded images are skipped.
Tracked changes: Word's tracked-changes markup is not interpreted — accept all changes first if you want the "final" text.
Macros & form fields: Skipped. These rarely matter for content comparison but are worth knowing if you live in macro-heavy templates.
Related comparison tools
How SnapTextCompare compares Word documents
Diff engine
Google's diff-match-patch (Apache 2.0), running in your browser. Character mode diffs raw characters; word and line modes encode tokens or lines first and diff those, then decode the result.
Similarity & importance
Similarity = 1 − Levenshtein / max(len). Importance weighs each change by category — money and dates score 90+, punctuation scores 3. Fixed rules classify a given diff; they do not determine meaning or whether an edit is safe.
Privacy
Files are read with the HTML5 File API and processed in your browser. No network request is ever made with your content — verifiable in the Network tab of your browser's DevTools. Full recent comparisons are saved in this browser's local History, even after closing the tab. Clear History to remove them.
DOCX body text is extracted with mammoth.js in your browser. Styling and layout are not compared. Headers, footers, comments and tracked revisions need separate review in a document-aware editor; keep the originals.
Word Document Comparison FAQ
Common questions about comparing Word documents online.