Compare PDF
Compare two PDFs: every word added or removed, with page numbers, and changed areas highlighted on the page.
By Syed Mubashir Ali · Last updated
How to Use Compare PDF
- 1Drop the original PDF on the left and the changed version on the right. Swap them with the arrow button if you put them the wrong way round.
- 2Read the text changes: a count of what changed, then each change with the page it's on in both files, the removed words in red and the added words in green, and a few words around it.
- 3Click 'See on the page' to open that page pair in the visual comparison, where areas that look different are boxed in red.
- 4Switch to Overlay to see both pages in one: red is only in the original, blue only in the changed PDF.
- 5To find every page that looks different, click 'Check every page'.
Frequently Asked Questions
How does it compare two PDFs?
Two ways. The text comparison reads the words of both files and lists every word added or removed, with the page it's on in each file. The visual comparison draws two pages side by side and boxes the areas that look different, which also catches changed pictures, colours, fonts and layout that the words alone don't show.
What if a page was added or removed?
The text comparison works on each document as a whole, not page against page, so an inserted page shows up as one change on the page where it was added, and the pages after it aren't reported as different. The visual check compares page 1 with page 1, 2 with 2 and so on, so after an inserted page it will flag the rest; pick the two pages to compare yourself in that case.
Does it catch formatting changes?
The text comparison doesn't: it compares words, ignoring line breaks and spacing, so text that was only re-wrapped or restyled isn't listed. The visual comparison does: a word made bold, a colour changed or a picture swapped shows as a boxed area.
Can it compare scanned PDFs?
Visually, yes. A scan is a picture of the page with no text in it, so the text comparison has nothing to read and says so; the visual comparison and 'Check every page' still find what changed. To compare the words of a scan, make it searchable with PDF Make Searchable first.
How big can the files be?
There's no fixed limit; it depends on your device's memory. Hundreds of pages are fine. In very long or very different documents, a passage that changed almost completely is shown as one block removed and another added, and the summary says when that happened.
Can I compare password-protected PDFs?
Not if they need a password to open: remove the password first (open the file in your PDF viewer and use Print → Save as PDF), then compare. PDFs that only restrict editing or printing open and compare normally.
Are my PDFs uploaded?
No. Everything happens in your browser; the file is never uploaded to a server, so it stays on your device.
About Compare PDF
Compare PDF shows what changed between two versions of a document: a contract before and after the other side's edits, a report draft and the final copy, an invoice re-issued with different figures. It lists every word added or removed with the page it's on in each file, and shows the pages side by side with the changed areas boxed.
Many PDF editors keep comparison for their paid plans; this one is free and runs in your browser with PDF.js, so neither file is uploaded. It reads the text the PDF contains, so it compares exactly what's in the file rather than a guess from a picture, and the visual view covers what words can't: pictures, layout and formatting.