Compare two PDF versions and explain the changes
Add the old and new version: get the exact before/after text with page numbers, plus an AI explanation you can check against it.
Drop Original
The earlier version
Drop Revised
The newer version
Try it 5× without an account. A free account includes 20 AI credits a month. See plans
What it does
AI compare PDF versions, explained
To compare two versions of a contract, policy or price sheet and understand what changed, add the original and the revised PDF: PDFBetter lists every changed passage with its before and after text and page numbers, then an AI explains what each change means, citing those quotes. The change list itself is computed without AI; the explanation costs 3 AI credits.
Read more
PDFBetter first computes the facts without AI: it extracts the text of both, lines up paragraphs, and lists each changed, added, removed or moved passage with the verbatim before and after text and its page number in each version. Changed amounts, percentages, dates and durations are pulled out separately.
Then, if you ask for it, the AI groups those facts into changes you can reason about — a longer confidentiality term, a new termination right, a different governing law — explains each in plain language and gives a low/medium/high materiality hint. The interpretation is clearly labelled and sits beside the facts, so you can check every explanation against the quoted text.
Compare PDF, its neighbor, highlights word-level differences in your browser and is the quicker check when you only need to see edits. This is a review aid, not a lawyer. The AI can misread intent or miss the significance of a change, and the comparison only sees text: images, signatures and layout changes are not part of it. The word-level and visual diff from Compare PDF is shown alongside for that.
How to do it
Compare two PDF versions and explain the changes in 4 steps
1Two versions
2Compare them
3Changes marked
- 1
Add both versions
Drop the original on the left and the revised version on the right, or pick two documents from your account.
- 2
Review the word diff
Added and removed words are highlighted page by page in your browser, free.
- 3
Explain the changes
With a free account, the factual change list is computed on our servers and the AI groups and explains it.
- 4
Check each card
Every explanation lists the before/after quotes and page numbers it is based on.
Example
Before and after
Two versions of a 3-page NDA, the second sent back by the counterparty as “minor edits”.
Four verified changes: confidentiality term 2 → 5 years, fee $1,200 → $1,500 and 30 → 45 days, governing law New York → Delaware, and a new 10-day termination clause; the AI marked the first three as high materiality.
Settings & formats
What you can control
- Facts only
- The verified change list with page numbers works without AI credits, and when AI is unavailable.
- Materiality hint
- Low, medium or high, as a pointer to what to read first — not a judgement of legal risk.
Input
Output
Good to know before you start
- Only text is compared. Changes to images, signatures, stamps, colors and layout are not explained (the visual overlay can show them).
- Scanned PDFs need OCR first; OCR errors show up as false changes.
- The AI interpretation can be wrong or miss why a change matters. It is not legal advice; verify against the quoted text and ask a professional when stakes are high.
- Very long documents are compared up to your plan's AI page cap (100 pages per document on Free and 600 on Pro); the AI explains up to a size limit and says when it stopped.
If something goes wrong
If something goes wrong
- It says no changes could be verified.
- The text of one version is likely image-only or uses an unusual encoding. Run OCR PDF on it and compare again.
- The AI explanation was skipped.
- You may be out of AI credits or AI is temporarily unavailable. The factual change list is still complete; nothing was charged.
AI compare PDF versions: questions people ask
How is this different from Compare PDF?
Compare PDF highlights word differences in your browser. This adds a paragraph-level change list with page numbers in both versions, changed figures, and an AI explanation of what the changes mean.
Can I trust the AI explanation?
Treat it as a starting point. Each card shows the verbatim quotes and pages it relies on, so you can check it. It is not legal advice.
What does it cost?
The word diff and the factual change list are free with an account. The AI explanation costs 3 AI credits per comparison, shown before you run it; if AI is unavailable or you're out of credits, you still get the change list and nothing is charged.
Are my files uploaded?
The word diff runs in your browser. For the change list and explanation both files are uploaded to your account, and the changed passages are sent to our AI provider under no-training terms.
Can I compare two versions of the same document?
Yes. Pick one document and two of its saved versions, or use the API or agent connection with two revision ids.
Does it catch a moved paragraph?
Yes. A paragraph that reappears unchanged elsewhere is reported as moved rather than deleted and re-added.
Does it work on Word files or scans?
It compares PDFs with a text layer. Convert Word files to PDF first, and run OCR on scanned versions; OCR misreads can show up as false changes.