Compare two PDFs
See the differences between two PDF documents side by side.
How to compare two PDF files online for free
- 1
Open the two PDFs you want to compare
Drop the original into the left slot and the revised copy into the right slot, or use the two Select PDF file buttons. Both documents open locally in your browser tab — nothing about either file is transmitted to reach this view.
- 2
Wait for the pages to be analysed
The tool walks through each PDF page by page and pulls out its text layer, updating a live Comparing… (X of Y pages) counter as it goes. Analysis runs three pages at a time and does not block the interface — you can start scrolling the side-by-side view immediately.
- 3
Read the verdict and open Visual Compare
Once every page has been examined, the header switches from the progress spinner to a clear summary like 4 of 32 overlapping pages differ. In Visual Compare mode, both documents render page-by-page next to each other with a red Differences detected banner above every page that changed.
- 4
Switch to Text Diff for the word-level view
Click the Text Diff tab to see the extracted text of both PDFs merged into a single word-level diff — added text in green, removed text in red, unchanged lines in grey. Use it to answer what exactly changed on the pages Visual Compare flagged.
Spot what changed between two versions
Someone sends a document back with a note that reads “same as before, just one small change” — and the whole review turns into a hunt for a single edit hidden inside dozens of pages. Reading two PDFs in parallel by eye is exactly how quiet changes slip through, whether that is a swapped payment term, a renamed party or a shifted date. This tool loads both files locally, pulls out the text layer of every page and marks every page whose text no longer matches its counterpart on the other side. You only review the pages that actually changed, and Text Diff mode shows the exact words that shifted so you never have to trust a casual “small change” again.
The only safe place to compare contracts
The PDFs people most often compare are also the most sensitive ones — contract drafts, non-disclosure agreements, supplier quotations, revised salary offers, board resolutions. Uploading two versions to a comparison website means the same confidential material is now sitting on someone else’s server, twice over.
This tool never sends either PDF anywhere. Both files are opened, rendered, text-extracted and diffed entirely inside your browser tab using PDF.js and jsdiff, with no upload endpoint on the other end. Once the tool code has loaded, you can drop your Wi-Fi and it will still finish the comparison — that is the honest test for whether a “private” tool is actually private.
An honest note about how comparison works
Visual Compare works at the page level: it reads each page’s text layer and flags the page as different if the text no longer matches its counterpart in the other file. That reliably catches edited sentences, changed numbers, renamed parties and inserted or removed paragraphs. Purely visual changes that do not touch the text — a repositioned logo, a recoloured shape — will not turn a page red on their own. For a word-by-word view of the actual edits, switch to Text Diff, which highlights every added and removed word across both documents. Scanned PDFs need a text layer (from OCR) to be comparable — pure image scans will look identical because there is no text to diff.
Side by side, page by page
Both PDFs render together in Visual Compare — page 1 of the original next to page 1 of the revised version, page 2 next to page 2, all the way down. Pages render lazily as you scroll into them, so you can start reviewing before the whole document is drawn.
Nothing missed on the pages that changed
Comparison reads the real text layer of each page and flags any page whose text no longer matches — a swapped number, a renamed party, an inserted clause, a shifted date. A red Differences detected banner appears above every flagged page so you cannot miss where to look.
A clear final verdict
As soon as analysis finishes, the header shows a plain-English summary like 4 of 32 overlapping pages differ so you instantly know the shape of the change. Until the last page is analysed the tool shows the honest in-progress counter instead of a misleading zero.
Handles big documents smoothly
Each page is drawn only when it scrolls into the viewport, and no more than two pages render at once. A 400-page contract behaves like a normal web page in the browser rather than freezing the tab while it processes the whole file up front.
When do you need to compare PDFs?
Reviewing a returned contract draft
You emailed a draft, the other side sent one back marked 'a few small edits' — but which ones? Drop both PDFs into the tool, wait for the analysis and jump straight to the pages that changed instead of re-reading the whole contract clause by clause looking for a rewritten sentence.
Checking a revised quotation or invoice
A supplier sends a new quote after a call and says only the delivery date moved. Compare the two PDFs to confirm no line item, unit price, tax rate or payment term quietly changed at the same time — the flagged-page count tells you at a glance whether the note was accurate.
Verifying the final version before signing
The approved copy went out for one last formatting pass and came back as final.pdf. Compare it against the approved.pdf you signed off on to make sure the last pass really was cosmetic before you attach a signature — a five-second check that closes a common last-mile mistake.
Confirming what a colleague updated
A shared report has been re-exported and you want to know what actually moved between your copy and today's version. Comparing the two exports surfaces every changed page and, in Text Diff, the exact wording that shifted — no more chasing 'what changed?' in Slack.
Frequently asked questions
How do I compare two PDF files for free?+
Open this page, upload the original PDF on the left and the revised PDF on the right, then wait a few seconds while the tool extracts the text of every page. When the header stops saying Comparing… it shows a summary like 4 of 32 pages differ, and the Visual Compare view marks every changed page with a red Differences detected banner. No account, no card, no watermark.
Are my files uploaded to a server?+
No. Both PDFs are opened, rendered, text-extracted and compared entirely inside your browser tab using PDF.js and jsdiff. There is no upload endpoint, no queue and no server-side processing, so neither the original file, the revised file nor the extracted text ever leaves your device.
What kinds of changes does it detect?+
The comparison reads the actual text layer of each page and flags any page whose text no longer matches the other side. That covers edited sentences, changed numbers, swapped names and dates, inserted or removed paragraphs, and reordered content. Purely visual edits that do not touch the text — a repositioned logo, a colour change on a shape — will not flip a page as different on their own.
Does it show exactly which words changed?+
Yes, in Text Diff mode. Visual Compare is the page-level view: it tells you which pages differ and shows them side by side so you can read the changes in context. Switch to the Text Diff tab and both PDFs are merged into a single word-level diff — added text highlighted green, removed text highlighted red, unchanged lines in grey — so you can see the exact edits without re-scanning each page.
Can I compare PDFs with different page counts?+
Yes. If the left PDF has 28 pages and the right has 32, the tool compares pages 1–28 as the overlapping range and lists pages 29–32 separately as existing only in the second document. The summary and the flagged-page count refer to the overlap, and the extra pages are still visible in the side-by-side view so you can review what was added.
Can I compare scanned PDFs?+
Only if the scans contain a text layer (for example, they were run through OCR before saving). This tool compares extracted text, and a pure image-only scan has no text to compare, so every page will appear identical or empty on both sides. If you need to compare raw scans, first run each through an OCR step so a text layer exists.
Is there a page limit?+
There is no artificial page cap. Pages are rendered lazily as you scroll and no more than two render at the same time, so a several-hundred-page PDF stays responsive rather than freezing the tab. The practical ceiling is your device's memory — very large or image-heavy PDFs on a low-RAM phone will feel slower than on a desktop.
Can I compare PDFs on my phone?+
Yes. The comparison workspace runs in mobile browsers the same way it does on desktop — pick both files, watch the progress counter, then swipe through the side-by-side view. Wide PDFs will need horizontal scrolling on a narrow screen, but every feature including Text Diff is available.
Can I compare password-protected PDFs?+
Not directly. The tool detects a password-protected file when you upload it and asks you to unlock the PDF first. Run each file through the free Unlock PDF tool (linked in Related tools below) to strip the password, then bring the unlocked copies back here to compare — the unlock step also runs in-browser, so nothing gets uploaded at any stage.
Do I need Adobe Acrobat to compare PDFs?+
No. Acrobat's Compare Files feature sits behind Acrobat Pro, and most online PDF comparison services either require signup or upload your files to their servers to run the diff. This page needs neither — it is free, works entirely inside the browser, and produces both a page-level Visual Compare and a word-level Text Diff without either PDF ever being transmitted.