Drop the original in the first box and the changed version in the second. PDF.js reads the text of both, pages are compared one to one, and the report lists removed lines in red and added lines in green, grouped by page, with a count per page. Download the report as a PDF if you want a record.
It compares words, not appearance. A moved logo, a font change or a re-flowed paragraph with identical wording does not show. Both files need real text; scans need OCR first.
Contract revisions, policy updates, two drafts of the same report, a resend that is supposedly identical. In every case the question is the same and the honest answer is hard to get by eye: what wording changed? Reading both versions side by side finds most of it. A diff finds all of it, and finds it in seconds, which is why programmers have relied on the technique for fifty years.
How to compare two PDFs
Put the older file first
The first box is the original, the second is the changed version. Swapping them reverses every colour, which reads backwards.
Add both PDFs
Drop or browse for each. Both are read into browser memory; neither is uploaded.
Press Compare
The text of every page is extracted, page 1 is compared with page 1 and so on, and differing lines are collected.
Read the report, download if needed
Changes are grouped by page with a count in each page header, so you jump straight to the pages that moved. The report downloads as a PDF for a record.
A reworded sentence shows as its old line removed and its new line added, side by side.
Extra pages in either file are reported as wholly added or removed.
Two confidential drafts never leave your machine.
How to read the comparison
- Red line with a minusIn the original, gone from the changed version
- Green line with a plusIn the changed version, absent from the original
- A red line directly above a green oneThe same line, reworded
- Page header with a countHow many lines changed on that page
- A page with no entriesText identical on that page
Only differences are shown, so a forty-page contract with two changed clauses produces a report a few lines long. Pages whose text is identical do not appear at all, which is the point: you read what changed and nothing else.
What it compares, and what it does not
Any change to the words
- Reworded clauses, changed figures, altered dates
- Added or deleted sentences and paragraphs
- Renamed parties, changed addresses
- Extra or missing pages
- A resend that is not actually identical
Changes that leave the text the same
- A moved logo, a resized image, a new page background
- Font, colour and layout changes
- A paragraph that reflowed across a page break (may show as moved)
- Changes inside images or scanned pages
- Form field values that were not part of the page text
For legal documents, policies and anything text-heavy, the wording is what matters, and the wording is what this surfaces. For a designed brochure where the layout changed, the comparison will report nothing and be right to.
Getting an accurate comparison
- Compare versions of the same document. Two unrelated files produce a long list of differences that means nothing. The tool shines when one file is a revision of the other.
- Both need a text layer. Select a word in each file. If it highlights, there is text. If not, run that file through OCR first, then compare.
- Watch the page alignment. If the new version inserted a page early, every later page is compared against the wrong one and the report fills with noise. Split or reorder so page numbers align, then compare again.
- Expect reflow noise. If a paragraph moved across a page break, it can show as removed from one page and added to the next. The words did not change; the page did.
Where a diff earns its place
- Contract revisions. Confirm the counterparty changed the dates and nothing else, in the time it takes to scroll a short report.
- Policy and terms updates. See precisely what a new version of a policy adds or removes before agreeing to it.
- Editing drafts. Check that only the intended edits went in and that a paragraph did not vanish in a bad paste.
- Verifying a resend. "Same file as before" is a claim. A diff with no entries is a fact.
Why both files stay in your browser
Comparing two files with an online tool means uploading both, which for a contract negotiation is two confidential drafts leaving your control at once, on a server the other side has never heard of. The comparison is a text operation any browser can perform, so there is no reason to accept that.
The tool is right above
Everything on this page runs in your browser. Scroll up, drop the file, and keep it on your machine.
Common questions
What people ask with the report on screen.
01What does the tool compare?
The text of the two PDFs, line by line, page by page. It shows which lines were removed, added or reworded. Text mode compares words only. The Visual overlay draws both pages on top of each other and colours anything that exists in only one version, which catches layout, image and colour changes.
02Does it work on scanned PDFs?
Only if both have a text layer. Run each scan through OCR first, then compare the OCR'd files.
03Can I download the comparison?
Yes. The report downloads as a PDF with removed and added lines marked, for a record or to share.
04How are pages matched up?
Page 1 with page 1, page 2 with page 2, and so on. If one file has more pages, the extra pages are reported as wholly added or removed. Align page numbers first if a page was inserted early.
05Why does a paragraph show as both removed and added?
Either it was reworded, in which case the old and new lines sit together, or it moved across a page break, in which case the words are unchanged and only the page differs.
06Does it show layout or image changes?
Yes, in Visual overlay mode. Both pages are drawn on top of each other: red pixels exist only in version A, blue only in version B, and a Differences only view hides everything the two share. Text mode lists the changed words; use both when a file was reformatted as well as edited.
07Are my files uploaded anywhere?
No. Both files are read and compared in your browser, and the report is generated there too.
08Is it free?
Free. Every tool, unlimited use, no signup.