How to Compare Two PDFs and See What Changed
Updated 2026-06-21
To compare two PDFs, open both files in a diff tool that extracts their text and lines them up side by side, then read the highlighted parts: added words on one side, removed words on the other. That is far more reliable than scrolling two documents and trusting your eyes to catch a flipped number or a deleted clause.
Compare two PDFs step by step
- Open the Compare Two PDFs tool.
- Load the original (the older or "before" version) on the left.
- Load the revised (the newer or "after" version) on the right.
- Read the side-by-side text diff. Changed words are highlighted in place — insertions and deletions are marked so you can see exactly what moved.
- Switch to the visual layout overlay if you also need to catch shifts in spacing, page breaks, or repositioned blocks.
- Export the list of differences to CSV or Excel when you need a record to share or review.
Because everything runs locally in your browser, neither PDF is uploaded to a server — which matters when the documents are contracts, NDAs, financial statements, or anything else you would not paste into a random website.
Read the redline like a pro
A text diff answers one question precisely: which words are different. Treat the highlights as a checklist rather than a summary.
- Added text shows up only in the revised version — new clauses, inserted figures, extra rows.
- Removed text shows up only in the original — deleted sentences, dropped terms, struck pricing.
- Changed values appear as a removal plus an addition in the same spot, so a price moving from one number to another reads as both at once.
Scan for the changes that actually carry risk: dates, dollar amounts, names, percentages, and negations like "shall" versus "shall not." Those are the edits most likely to slip past a manual read.
Common pitfalls and how to handle them
Scanned PDFs have no text. If a page is an image of a document rather than real text, there is nothing to diff. You will need a text-based PDF — one where you can select and copy words — on both sides. The tool flags a side that appears to be scanned so you are not misled by an empty comparison.
Reordered paragraphs look like big changes. Moving a block counts as a deletion in one place and an addition in another. The diff is correct; just read both highlights together before assuming text was rewritten.
Layout-only edits. A change to fonts, margins, or page breaks may not alter a single word. That is what the visual overlay is for — use it alongside the text diff, not instead of it.
Export the differences
Once you have the diff, send the CSV or Excel export into your review workflow — attach it to an approval, drop it in a change log, or hand it to a colleague who only needs the list of what moved.
Ready to see what changed? Open Compare Two PDFs and load your two versions — it all stays on your device.