When a revised document comes back, the question is always the same: what changed? Reading two versions side by side takes ages, and small edits slip through. Compare PDF draws each page of both files and marks every area that differs. View them side by side with scrolling kept in step, lay one over the other, or see only the differences. Added, removed and moved text is listed page by page, and you can download a report.
How to use Compare PDF
- Add two PDFs: the original first, then the revised version.
- Select Compare PDFs.
- Switch between the side by side, overlay and difference views.
- Open the list of changes and jump to each changed page.
- Download the PDF report if you need to keep a record.
Three ways to look at changes
- Side by side shows the original in one column and the revised version in the other. The two columns scroll together, so the same part of each page stays lined up.
- Overlay puts the revised page on top of the original, and a slider fades between them. This makes small shifts easy to notice.
- Difference view blends the two pages so that anything identical turns black and only the changes stay visible.
- Red boxes: In every view, red boxes mark the areas where the pages differ. You can hide the boxes, or show only the pages that changed.
Added, removed and moved content
- Text blocks and images are read: Besides comparing the look of each page, the tool reads its text blocks and images.
- Added and removed: Anything on the revised page that isn't on the original is listed as added, and anything that disappeared is listed as removed.
- Moved: A block that's still there but in a different spot is listed as moved, which usually means the layout changed.
- Why it helps: Pages that changed size are flagged too. This makes it quick to tell a changed number from a paragraph that just moved down.
- Scanned pages have no text blocks, so only the visual boxes appear for them.
What the comparison can and can't tell you
- Pages match by position: Pages are compared by position, so page 3 is checked against page 3. If a new paragraph near the start pushes everything down, later pages will show changes too.
- When everything shifts: When that happens, compare matching parts separately with Extract Pages.
- Page limits: The viewer shows the first 30 pages and the report covers up to 60.
- Blocks, not single words: The added and removed lists show whole text blocks instead of single words, so read the boxed area to find the exact edit.
- For documents that aren't versions: For questions across documents that aren't versions of each other, try the AI PDF Workspace.
Keeping a record of the review
- What the report contains: The PDF report starts with a summary page: both file names, their page counts and how many pages changed. It then shows each changed page side by side with the differences outlined, plus a short list of added and removed text.
- When it's handy: It's handy when you need to show a client or manager what changed, or keep proof of what you checked.
- Difference images: If you'd rather have images, download the difference images as a ZIP.
- Lock the approved version: Once a version is approved, lock it with Flatten PDF or Protect PDF.
When people use Compare PDF
Checking contract revisions
Confirm the version sent for signature matches the draft you agreed, and spot any clause that changed.
Reviewing reissued drawings
See whether a revised plan changed anything beyond the listed amendments.
Verifying regenerated reports
Check that a new report run kept the same layout and only the figures you expected changed.
Limitations to know
Pages are compared by position, so inserted content makes later pages differ. The viewer shows 30 pages and the report 60. Added and removed lists work on text blocks, not single words, and need real text instead of scans. Pages of different sizes are scaled to match.
Compare PDF: common questions
Does it list the words that changed?
It lists the text blocks that were added, removed or moved on each page, and boxes every changed area. Read the boxed area to see the exact words.
Why does every page after a certain point show changes?
Content has probably shifted, for example after a paragraph was added, so the same page number no longer lines up. Compare matching sections instead.
Can it compare scanned documents?
Yes, visually. Two scans of the same paper rarely line up perfectly, so slight shifts can show as changes, and the added and removed lists stay empty.
How many pages can I compare?
The viewer shows the first 30 pages and the PDF report covers up to 60. Split longer files and compare them in parts.
Can I compare more than two files?
No. Compare exactly two PDFs at a time.