Quick answer
- Upload the older file and the newer one to Compare PDF. It lines up every page and boxes the parts that are different.
- Added, removed and moved text is also listed page by page, so you don't have to read the whole file to find the edits.
- You can view the two files side by side, laid over each other, or as a difference view that hides everything that's the same.
- Scanned PDFs can only be compared visually, since there's no text underneath to read and list.
How do I compare two versions of a PDF?
Open Compare PDF, add the original file first and the revised one second, and run the comparison.
- Add both files: the order matters, so put the older version first and the newer one second.
- Run the comparison: the tool draws each page of both files and marks every area where they differ.
- Check the list: added, removed and moved text blocks show up page by page next to the boxed pages.
- Save the result: download a PDF report, or save the difference images if you'd rather keep pictures.
What do the side by side, overlay and difference views show?
They're three ways to look at the same changes, and each one makes a different kind of edit easier to spot.
- Side by side: the original sits in one column and the revised page in the other, scrolling together so the same spot stays lined up.
- Overlay: the revised page sits on top of the original, and a slider fades between them, which is good for catching small shifts.
- Difference view: anything identical on both pages turns black, so only the parts that changed stay visible.
- Red boxes mark the changed areas in every view, and you can hide them or show only the pages that changed.
What do "added," "removed" and "moved" mean in the results?
They describe whole text blocks, not single words, so you still need to glance at the boxed area to see the exact edit.
- Added: text or an image that's on the new page but wasn't on the old one.
- Removed: text or an image that was on the old page and is gone from the new one.
- Moved: a block that's still there, just in a different spot. This usually means the layout changed, not the wording.
- A block listed as changed is normally a sign a number, a date or a name was edited inside it.
Why do all the pages after one edit suddenly show as changed?
Because the tool checks page 3 against page 3 and page 4 against page 4. Add a paragraph near the start and everything after it shifts down by a page.
- This is normal for a long contract or report where one new clause pushes the rest of the text down.
- Pull out the part that actually changed with Extract Pages and compare that smaller piece on its own.
- The viewer shows the first 30 pages, and the downloadable report covers up to 60, so split longer files before comparing them.
- If a whole document was reordered rather than edited, expect most pages to show as different even though the content is the same.
Can I compare two scanned PDFs?
Yes, but only by sight. A scan is a picture of a page, so there's no text underneath for the tool to read and list.
- You'll still see the red boxes marking where the pages look different.
- The added, removed and moved lists stay empty, because there's no text layer to pull them from.
- Two scans of the same paper rarely line up pixel for pixel, so a small tilt or shift can show up as a difference that isn't really one.
- Running the file through OCR PDF first adds a text layer, but the comparison still works on the pixels, not that hidden text.
How do I keep a record that I checked a document for changes?
Download the comparison as a PDF report before you do anything else with the files.
- The report opens with a summary: both file names, how many pages each has, and how many pages changed.
- Each changed page follows, shown side by side with the differences outlined and the added or removed text listed underneath.
- Once a version is approved, lock the file with Protect PDF so nobody can open or change it without the password.
- Keep the report with the final file. It's proof of what you checked, not just that you checked something.
Try the tools
Try it on your own file. The tools are free and you don't need an account.
Common questions
Can I compare a Word document against a PDF?
Not directly. Compare PDF only reads PDF files, so convert the Word file first with Word to PDF, then compare the two PDFs.
Can I compare three or more versions of the same file at once?
No, the tool compares exactly two files at a time. Compare version one against version two, then version two against version three, as separate runs.
Does comparing two PDFs change either of the original files?
No. The tool only reads both files to build the comparison. Your original and revised PDFs stay exactly as you uploaded them.
Will it catch a change in font or text size, not just the words?
Yes. Every page is checked visually as well as by its text, so a font swap or a resized heading shows up as a boxed difference even if the words stayed the same.
What if the two files have a different number of pages?
The comparison still runs. Pages that exist in only one file show up as entirely added or removed, and the rest are matched by their position as usual.
This post is general information about working with PDFs, not legal or security advice. Check anything important with someone qualified. Posts are written with AI help, based on how our tools actually work. About VelloDoc
