How to compare two PDF files and see what changed
Quick answer
Add both PDFs to a PDF comparison tool. It extracts the text from each and shows you every line that was added, removed or changed - no need to read both documents side by side.
- 1Add the original PDF.
- 2Add the changed PDF.
- 3Read the line-by-line differences.
- 4Copy or download the comparison.
Free, no sign-up, and your file is read on your own device rather than uploaded.
Eyeballing two versions of a PDF side by side works for a one-page document. For a multi-page contract, report or policy, a single reworded clause or a changed figure is exactly the kind of thing reading alone misses.
A PDF comparison tool solves this the same way version control solves it for code: pull the text out of each document and match it line by line, so only genuine differences are flagged rather than making you reread everything.
Step by step
Read the differences
Every line is matched between the two - added lines, removed lines and unchanged lines are marked separately.
Compare Two PDFsCopy or download the result
Keep a record of exactly what changed, without keeping both full documents open.
Compare Two PDFs
Tips
- This compares text, not visual layout - two PDFs with identical wording but different fonts, colours or formatting will show as identical, because the comparison works from extracted text.
- A paragraph that moved to a different page but was not reworded is still recognised as unchanged, because lines are matched by content, not by page number.
- If either PDF is a scan, there is no real text to extract - run OCR on it first, then compare the recognised text.
Common problems
The whole document shows as one big change instead of specific lines.
This happens when the two documents have too little text in common to line up meaningfully - usually because they are genuinely different documents rather than two versions of the same one, or one is a scan with no extractable text.
A change I know exists is not showing up.
The comparison only sees extracted text. A change that is purely visual - a colour, a font, an image swapped for a similar one - will not appear, because neither PDF's extracted text carries that information.
Frequently asked questions
- Can I compare two PDFs without installing any software?
- Yes - this runs entirely in your browser. Add both files, and the comparison happens on your own device with nothing uploaded.
- Does this work on scanned PDFs?
- Not directly. A scan is a picture of a page with no real text to extract - run the OCR workspace on each scan first, then compare the recognised text instead.
- What is the difference between this and Text Diff Checker?
- Text Diff Checker compares text you paste in directly. Compare Two PDFs does the extraction for you first, so you can hand it two PDF files instead of copying their contents out by hand.
- Will formatting differences show up as changes?
- No - only the text itself is compared. Two PDFs with identical wording but different formatting will show as identical.
- Is either PDF uploaded anywhere?
- No. Both files are read and compared entirely in your browser.
Doing several things to this PDF?
"Editing a PDF" is usually one of five different jobs. Open the file once and you can do all of them in sequence - reorder the pages, mark it, number it, sign it and shrink it - then download once at the end.
How to edit a PDF without AcrobatRelated PDF tools
- PDF to TextPull the words out of a PDF as plain text or structured Markdown.
- Text Diff CheckerCompare two versions of a text and see precisely what changed.
- OCR Text ExtractorUpload an image or a scanned PDF and get real, selectable text back - processed on your own device.