How to compare two PDF files and find every difference

Last updated: 19 October 2026

Reading two versions of a document line by line is slow, and the eye skips exactly the small edits that matter: a changed number, a removed sentence, a moved date. A PDF comparison tool does the line-by-line work for you and shows only what changed.

What you need

• The original or approved PDF. We call this the reference.
• The revised PDF you want to check.
• A modern browser such as Chrome, Edge, Firefox or Safari. Nothing to install.

Step by step

1. Open compare2pdf.com. The tool loads with a sample pair so you can see how results look.
2. Click Replace in the left pane, or drop your original PDF onto it. This becomes the reference.
3. Click Replace in the right pane and open the revised PDF. The comparison runs as soon as both files are open.
4. Read the Findings list on the right. Each item shows the type of change, the page numbers on both sides and the text before and after.
5. Click a finding to jump to it. Both documents scroll to the same place and the change is outlined on each.
6. Press J and K to move to the next and previous finding without using the mouse.

Reading the results

• Changed: text was replaced. The old wording is struck through and the new wording is highlighted.
• Added: text exists only in the checked PDF.
• Removed: text exists only in the reference. A small marker shows where it used to be in the checked PDF.
• Form field: a fillable field has a different value, or exists in only one of the files.

Use the filter chips above the list to hide categories you do not need, for example to review only removed text. Tick Ignore case if capitalisation changes are not important to you.

Exporting a marked-up copy

Click Export with findings to download the checked PDF with every finding boxed and numbered in colour. A summary page at the end lists each finding with its page numbers, which is useful when you need to send your review to a colleague or attach it to an approval.

Tips for accurate comparisons

• Compare PDFs that were exported from software such as Word or Google Docs. Scanned pages are images and contain no text to compare.
• If a document was re-flowed and many lines moved, the synced scrolling still keeps matching text side by side.
• Your files are processed in your browser and never uploaded, so it is safe to compare confidential documents.