How to use the Compare PDF
Step 1: Drop the original PDF into the first box and the changed PDF into the second.
Step 2: Press Compare PDFs. The text of both files is read and compared page by page.
Step 3: Read the summary, then look through the pages with differences: red lines were removed and green lines were added.
Step 4: Tick Also show unchanged lines if you want the surrounding context.
Features and benefits
Line-by-line differences
Added and removed lines are highlighted in clear colours, with signs for people who cannot rely on colour.
Page-by-page view
Only pages with differences are shown, so you can go straight to the changes.
Page count check
You are told if the two files have a different number of pages.
Context on demand
Show unchanged lines when you need to see where a change sits.
Private
Both PDFs are read on your device and never uploaded.
How the comparison works
The tool reads the text of each page, groups it into lines in reading order and then finds the longest run of lines the two versions share. Lines that appear only in the original are marked as removed, and lines that appear only in the changed file are marked as added. Pages are compared with the page in the same position, so if a page is inserted early, later pages can show as changed.
What it cannot compare
Only text is compared. A changed image, a different colour, a moved paragraph that keeps the same words on the same page, or a layout tweak will not appear. PDFs made from scans contain pictures of text rather than text, so the tool reports that there is nothing to compare. For those, run text recognition (OCR) in other software first.
Example use cases
Contract revisions
See what the other party changed between two drafts.
Report updates
Check what changed between this month's and last month's report.
Proofreading
Confirm that only the intended corrections were made.
Policy changes
Spot differences between old and new versions of terms or policies.
Frequently asked questions
Does it compare images and layout?
No. It compares text only. Changes to images, colours or layout will not be shown.
Why does it say no text was found?
The PDFs are probably scanned images. They contain pictures of text, not real text, so there is nothing to compare.
Why do many pages show as changed after I inserted one page?
Pages are compared by position. An inserted page shifts the pages after it. Compare the sections separately or remove the extra page first.
Are my files uploaded?
No. Both PDFs are processed in your browser.
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Last updated 9 November 2026.