How to compare two PDFs
- Add the original document on the left and the newer version on the right.
- Press Compare. Both files are read and their text is lined up page by page.
- Read the result: added lines are green and marked
+, removed lines are red and struck through, unchanged lines sit between them for context. Pages with no changes are skipped. - Press Save the report to keep a plain-text record of the differences.
About this tool
Comparing two PDFs shows what changed between drafts. This free comparison tool extracts the text of both documents in your browser and reports the differences line by line.
The situation is familiar to anyone who deals with contracts or policy documents: a revised version arrives, described as containing "a few small updates", and there is no track-changes view because it is a PDF. Reading forty pages twice to find three altered sentences is a poor use of an afternoon, and skimming reliably misses the clause that matters. This lines the two documents up and points at the differences.
It compares text, not appearance. A changed word, an inserted clause, a deleted paragraph or a renumbered section will all show up. A change of font, a moved logo, a different image or an altered chart will not, because none of those change the words on the page. It also needs real text to work with — two scanned documents contain pictures of words, not words, so run them through OCR first. Both files are read entirely on your device, which matters when the two versions of a contract you are diffing are both confidential.
Frequently asked questions
- Are both documents uploaded?
- No. Both are read in your browser and neither is transmitted. Nothing about the comparison involves a server.
- Does it show formatting changes?
- No. It compares the text. Changes to fonts, colours, images or layout will not appear unless the words changed too.
- Why does it say there are no differences when the files clearly differ?
- Most likely one or both are scans, which contain images of text rather than text. Run them through OCR first and compare the results.
- Can I compare documents with different page counts?
- Yes. Pages are compared in order and any extra pages are reported as wholly added or removed.
- Why are some pages missing from the report?
- Pages with no textual differences are skipped so the report shows only what changed. The summary line counts them.