Document comparison with source evidence
See what changed between two document versions.
Upload an older and newer PDF or Word file and see every detected wording change free. Add a $9 AI Review when you want DocDiffAI to prioritize language that may affect cost, time, obligations, rights, or risk.
Agreement revision · 38 pages
Evidence ledger
Payment terms · page 7
Net 30 Net 60
Termination · page 19
A new notice requirement was added. The report quotes the source language and names the page.
How it works
Compare free, then pay only if you want the review done for you
You bring two versions. DocDiffAI builds the source-linked wording diff for free. A paid AI Review ranks what looks consequential.
1 · Upload
Add both versions
Older and newer contracts, proposals, policies, or reports. PDF or Word (.docx).
2 · Compare
Read the change list
Additions, deletions, and revised wording, with the ones most worth a second look called out first.
3 · Verify
Open the source
Follow each finding to the quoted language and page. Nothing asks you to trust a summary alone.
Remote MCP for document comparison
Give your agent a source-cited document comparison tool.
Connect Claude, Codex, Cursor, or another MCP client to DocDiffAI. Your agent can submit two PDF or Word versions, check progress, and retrieve the same cited report a person gets in the browser. Not for code diffs.
POST /mcp
Attach two versions. Ask what changed.
- create_comparison
- Send the older and newer ChatGPT attachments directly to DocDiffAI.
- get_comparison
- Check progress and source coverage.
- unlock_comparison_report
- Unlock a completed report when report access is available.
- get_comparison_report
- Read the unlocked, source-cited report.
Sample report
A full sample report you can read today
We compared two versions of a public procurement invitation. Two small edits doubled an optional extension from 12 months to 24 months. The sample shows both findings with source quotes, the same way your report will.
- Documents
- 2 PDFs
- Length
- 10 pages each
- Term changes found
- 2 of 2
- Source coverage
- Complete
Why people use it
Manual redlines miss quiet, expensive edits
A single number in an extension clause or payment window is easy to overlook when you are reading for “big” redlines. DocDiffAI is built for that kind of check: full change coverage, then a short list of findings that may actually move money, timeline, or risk.
For version reviews
Older draft vs. final, counterparty mark-up vs. your last send, or two “final” PDFs that are not quite the same.
For people who must verify
Legal, procurement, ops, and founders who will not accept a summary they cannot open against the file.
Free tool
Need the money terms from one incoming contract?
If you only have one file, pull payment, term, notice, and liability language with a source page.
Industry statistics
Official counts you can cite
Public construction, insurance, and legal numbers, with a source on each line. These are not DocDiffAI customer counts.
Source-cited
Findings point back to the exact document language and page.
Private by default
Secure links, controlled access, and files scheduled for deletion after three days unless you keep the report longer.
Built for business docs
Contracts, vendor proposals, policies, and working reports in PDF or Word.
Common questions
Straight answers before you upload
Do I need an account?
No. Upload two files and keep the comparison page open. Add an email only if you want a backup link. Create an account later if you want saved comparisons and billing.
Which files can I compare?
PDF and Word (.docx), up to 50 MB each and 600 combined pages. Searchable text works best; scanned PDFs and complex tables may take longer.
How is this different from Track Changes?
DocDiffAI compares the content of two finished files, even when revision history is missing or the versions are PDFs. The free diff lists detected wording changes with source-page citations. A paid AI Review prioritizes what may matter.
How accurate is the comparison?
Every published finding points to quoted source language and a page you can check. If the evidence cannot be verified, DocDiffAI holds the report instead of presenting incomplete findings. Review the cited text before acting; DocDiffAI is decision support, not legal advice.
How long does a comparison take?
Processing starts automatically, and your free diff appears on the comparison page when it is ready. If you add an email, we also send a backup link. Long documents, scanned pages, and complex tables can take longer than a typical comparison.
What happens to my files?
Files are encrypted in transit and stored privately. Unpaid uploads are scheduled for permanent deletion after three days. Paid reports and source files remain available for up to three years unless you delete them sooner. Read the Privacy Policy.
Are my documents used to train AI?
Free comparisons may be used to evaluate and improve DocDiffAI. Paid content is not used for product-training datasets without your separate permission. Read the Privacy Policy.
What does it cost?
The deterministic wording diff is free for document pairs up to 100 combined pages. An AI Review is $9 for up to 100 combined pages and does not include chat. Pro is $39 per month for 10 AI Reviews, cited chat, and up to 600 combined pages per pair. Every paid purchase includes a 30-day money-back guarantee.
Ready to check a pair of files?
Upload two versions, get a source-cited report, and keep or delete when you are done.