Compare Two PDFs — Spot Every Difference
Overlay two versions of a PDF page by page and see what changed, highlighted in red and cyan.
When a document goes through several rounds of edits, it is easy to miss what actually changed. This tool lines up two versions of the same document page by page and highlights the areas that differ. It is handy for checking revised contracts, quotes, or any file that has been edited back and forth.
How to compare two PDFs (3 steps)
- Select both versions of the document (two files).
- The tool renders them and overlays each page on its counterpart, highlighting the differences.
- Download the comparison PDF.
When to use it
- Revised contracts — the other party sent a new version and you need to know what they changed.
- Quotes and price lists — check which figures changed between versions.
- Plans and printed layouts — find elements that moved or were added.
How to read the result
After you pick two files, matching pages are laid on top of each other (page 1 with page 1, page 2 with page 2, and so on), and a comparison PDF is generated:
- Black — identical in both files.
- Red — only in the first file (removed or changed).
- Cyan — only in the second file (added or rewritten).
If the two files have a different number of pages, any extra pages are shown entirely in that file's color.
Limitations to know
- The comparison is based on position on the page, not word by word. If a new paragraph is inserted and pushes the content down, every line after that point will appear as overlapping red and cyan. It works best on files with the same layout where only a few spots were edited.
- The output is an image-based file meant for reviewing differences, not a document to send on.
FAQ
Can I compare scanned documents?
Yes, but scans that are slightly tilted or shifted will show as overlapping red and cyan across the whole page. Files exported from the same program give much cleaner results.
What if the page counts don't match?
Pages that can be paired are compared. Any extra pages are shown entirely in the color of the file they came from.
Is it useful for checking a contract before signing?
Very. You can see at a glance which parts the other party changed from the original draft.
Can I compare a scan against the original digital file?
You can, but it is not recommended. Scans are usually slightly skewed or a little different in size, so the whole page ends up as overlapping red and cyan and is hard to read. It works well with files exported from the same program.
Which file should I select first?
Select the original as the first file and the revised version as the second. Red then marks what was removed and cyan marks what was added.
Can I keep the result as evidence?
It is useful as a review aid, but always keep both original versions as well.
Does it compare text or appearance?
Appearance. Pages are compared by what sits where on the page, not word by word.