Compare two PDF files and see exactly what changed

What is PDF Compare?

How to use PDF Compare

1. Step 1

   Choose the previous version

   Drop the original PDF on the first panel, or browse for it. Your browser checks it is a readable PDF and shows its page count.

2. Step 2

   Choose the new version

   Add the revised PDF the same way. You can replace or remove either file before comparing.

3. Step 3

   Compare the documents

   Choose Compare documents. Both files are compared and the result opens below, with progress shown while it runs.

4. Step 4

   Review each change

   Step through the changes with Previous and Next, filter them, and check the evidence for each one against both PDFs.

What DiffNexa finds

How the results show their evidence

The change navigator

Every change is numbered and grouped by the page it is on. Search the changes, or filter by kind (added, removed, changed, moved), by type (content, values, dates, pages) and by page.

The Pages view

Both PDFs are drawn side by side from your own files, with every change outlined where it is. Choosing a change turns each version to the page its evidence is on.

The Evidence panel

For the change you choose: the values before and after with the difference worked out, and the exact wording quoted from each version with its page number.

The List view

Every change as a card you can read from top to bottom, with the before and after side by side — useful for reviewing a long list in one pass.

What happens to your files

Limitations

• Scanned pages — pages that are pictures of text — are detected and flagged, but their text is not read yet. Reading it is planned.
• Images, logos, signatures and visual layout are not compared yet. A change with no text behind it is not found.
• Tables are compared as their text and values; row, column and cell structure is planned. A changed figure inside a table is still found.
• Formatting such as font, colour, bold or spacing is not reported as a change.
• Complex layouts — many columns, or text boxes placed freely on the page — can be read in a different order from how they look. The evidence always shows exactly what was read.
• Password-protected and damaged PDFs are refused with an explanation. Each file can be up to 50 MB and 500 pages.

Optional: AI Change Analyst

Questions

How does PDF Compare work?

It reads the text of every page in both PDFs, in reading order, and lines the two versions up as whole documents. Wording is compared word by word; numbers and dates are compared as values. Differences that are only a page break, a reflowed line or a page number are set aside, and each remaining change is reported with where it is in both files.

Are uploaded PDFs stored?

No. Your PDFs go to the comparison service, are used only to produce your result, and are discarded when it is returned. There is no account and no history, and the comparison sends nothing to any AI service.

Can it compare scanned PDFs?

Not yet. Pages that are images with no text behind them are detected and flagged rather than silently mis-compared. Reading that text is planned for a later release.

How are changes shown?

As a numbered list grouped by page, with both PDFs drawn side by side and each change outlined in place. Choose a change to see its values before and after and the wording quoted from each version, and use Previous and Next to move through them.

Will a page break or a new page number count as a change?

No. The whole document is compared in reading order, so text that moved to another page is matched to itself, and page numbering is not treated as content.

Why is the compare button sometimes disabled?

Both documents must be readable and the comparison service must be reachable. A button that looked ready but produced nothing would be worse than one that explains itself.

Which files are supported?

PDF only, up to 50 MB and 500 pages each. Password-protected and damaged files are refused with a clear explanation of what to do. For Word documents, use DOCX Compare.