Compare PDF Files and See Every Change
Compare PDF files in your browser: drop in two versions and see exactly what was added, removed, or moved. Your documents are never uploaded.
Nothing is uploaded
Both documents are parsed and rendered on your own device. You compare PDF files without a server ever receiving them.
Word-level text diff
Additions and deletions are marked word by word, not line by line, so the diff stays precise.
Visual overlay
A pixel comparison catches moved logos, changed figures, and layout shifts.
Ten languages
The full interface and guide are available in ten languages, not just English.
In short: Drop in two versions and this tool will compare PDF files word by word and pixel by pixel, with a counter for every edit. It runs entirely in your browser, has no daily cap, and needs no account. Scanned pages without a text layer are detected and flagged, so you know when to run OCR before you compare PDF documents that came from a scanner.
Why Comparing PDFs by Eye Fails
Someone sends back a contract marked "minor edits." You scroll through it, everything looks familiar, and you sign. Three weeks later you find out the payment window moved from thirty days to sixty, and the indemnity clause picked up an exception that was not there before.
This is not carelessness. Reading two documents side by side is a task human attention is genuinely bad at, and it gets worse in exactly the situations where accuracy matters most. That is the whole reason to compare PDF files with a tool rather than with your eyes: long documents, tight deadlines, and revisions that were described as trivial are precisely where a manual read breaks down.
Familiar text is skimmed, not read
Once you have read a paragraph, your eye stops processing it word by word and starts recognising its shape. A single changed number sits inside a sentence that still looks exactly right. The change you are least likely to catch is the one inside text you have already reviewed.
One edit shifts everything after it
Add a clause in the second paragraph and every line below it moves. Suddenly page four of the new version does not line up with page four of the old one, and side-by-side scrolling stops being useful. The document now looks different everywhere, which makes the one real change harder to find, not easier.
The expensive changes are the small ones
Rewritten sections are obvious. The edits that cause real damage are a swapped figure, a flipped "shall" to "may", a deleted "not", or a date pushed by a month. They are small enough to survive a careful read and large enough to change what the document means.
What It Means to Compare PDF Files
To compare PDF files is to check two versions of a document against each other and surface every difference between them: text that was added, removed, or edited, and anything that moved or changed visually on the page.
There are two different questions hiding inside that, and good tools answer both. The first is what the words say: extract the text from both files and align it so you can see, word by word, what is no longer there and what is new. The second is what the page looks like: render both versions as images and compare them pixel by pixel, which catches things text alone can never show you — a resized logo, a redrawn chart, a shifted table, a signature block that moved.
Neither answer is complete on its own, so any serious attempt to compare PDF documents needs both. A text diff will miss an image that was swapped for a different one. A visual overlay will light up an entire page as changed when all that happened is a paragraph got one word longer and everything reflowed. This is why the tool on this page lets you compare PDF files both ways and switch between them on the same pair without starting over.
How to Compare PDF Files in 3 Steps
There is no setup, no account, and no upload step. To compare PDF files here you only add them, and the comparison starts by itself as soon as both are in place.
- 1
Add both versions
Drop the original into the left panel and the revised file into the right. Order matters for how changes are labelled: what is missing from the left is a deletion, what is new on the right is an addition. You can compare PDF files of different lengths, because mismatched pages are handled explicitly rather than forced into pairs.
- 2
Read the summary, then the pages
The bar at the top counts words added, words removed, and how many pages changed. Below it, both documents are shown side by side with deletions marked in red on the left and additions marked in green on the right.
- 3
Step through every change
Use the previous and next buttons — or the left and right arrow keys — to jump from one difference to the next. The counter tells you how many there are in total, so you can be sure you have seen all of them rather than hoping you scrolled past nothing.
If you would rather check the layout than the wording, switch to visual mode at any point. Both modes compare PDF pages from the same two files, so moving between them costs nothing.
Two Ways to Compare PDF Files: Text and Visual
There are two ways to compare PDF files, they answer different questions, and choosing the wrong one is the most common reason people conclude that nothing changed when something did.
Text mode — what the words say
The text layer is pulled from both PDFs, reassembled into continuous paragraphs, and aligned word by word. Deletions are highlighted in the original, additions in the revised file. Use this to compare PDF contracts, policies, reports and manuscripts, or anything where the wording is the point. It needs a real text layer, so it will not work on scans.
Visual mode — what the page looks like
Both pages are rendered and compared pixel by pixel, and the regions that differ are boxed. Use this for drawings, invoices, forms and slides, or anything with figures and images. It works on scanned documents too, because it never needs to read the text, though it will also flag differences that are purely cosmetic.
A practical habit: start in text mode to find out what the document now says, then compare PDF pages again in visual mode to confirm nothing moved that should not have. Text mode tells you the meaning changed; visual mode tells you the page changed. On a revised document, those are rarely the same set of changes.
How to Compare PDF Scans
A scanned PDF is a picture of a document, not a document. The page you are looking at is an image, and there are no characters behind it to extract. Every text-based tool that can compare PDF files, including this one, has nothing to read. That is why scans are where most attempts quietly fail: the tool reports no differences, and the reason is that it could not see any words at all, not that the words match.
Rather than let that pass silently, this tool checks each page for a text layer and tells you which pages do not have one. You then have two honest options. Visual mode works immediately and will compare PDF scans as pixel regions, which is often all you need. But if you want a real word-level diff, to know that thirty became sixty rather than just that a region of the page looks different, the scan has to be given a text layer first.
That is what OCR does: it reads the characters out of the image and writes them back into the file as a searchable text layer, without changing how the page looks. Once both scans have been through it, they compare like any other pair of documents. Run OCR on a scanned PDF first
Other Ways to Compare PDF Files
Being honest about this is more useful than a marketing table. Several established tools also compare PDF files locally, and any page claiming to be the only private option is overstating it. What is genuinely hard to find is all of these properties in one place.
| What matters | This tool | Commonly elsewhere |
|---|---|---|
| Price | Free, no tier above it | Free tier with paid features above it |
| Where files are processed | Always in your browser | Mixed — some local, many upload |
| Usage limits | None | Daily caps are common |
| Account required | Never | Sometimes, and required for export |
| Interface languages | Ten | Often English only |
| Scanned pages | Detected and flagged | Usually fails silently |
To be specific about the row that matters most: PDF24 states that its comparison runs in the browser, and Diffchecker says the same for PDF-to-PDF comparisons. Those claims appear accurate, and we are not going to pretend otherwise to look better. Where this tool differs is the combination: free with nothing gated behind an upgrade, no daily cap, no account, ten interface languages, and an explicit warning when a page has no text layer instead of a result of zero differences that quietly means nothing was read. One thing it does not do is compare PDF files against Word documents. That would require either a server or a heavyweight converter, and neither belongs in a tool built on the promise that your documents never leave the device.
Complete PDF Tool Suite
Discover our comprehensive collection of PDF tools designed to handle all your document needs
PNG to PDF
Bind PNG images into a single, print-ready PDF
JPG to PDF
Convert JPG images to PDF format
Merge PDF
Combine multiple PDF files into one
Compress PDF
Reduce PDF file size efficiently
PDF to PNG
Convert PDF pages to PNG images
PDF to JPG
Convert PDF pages to JPG images
PDF to Text
Extract text content from PDF files
Split PDF
Split PDF into separate pages
Edit PDF
Edit and annotate PDF documents
Organize PDF
Organize and rearrange PDF pages
Rotate PDF
Rotate PDF pages and save permanently
Page Numbers
Add page numbers to PDF with live preview
Watermark PDF
Add a text watermark to PDF with live preview
HEIC to JPG
Convert iPhone HEIC photos to JPG
Delete PDF Pages
Remove unwanted pages and download a clean PDF
Extract PDF Pages
Save selected pages as a new PDF or separate files
Sign PDF
Draw, type, or upload a signature and place it on any page
Resize PDF
Change page size to A4, Letter, or custom dimensions
Crop PDF
Trim margins, drag-select, or auto-crop white space
Flatten PDF
Make forms read-only — keep text searchable or lock to image
PDF Metadata
View, edit, or strip author, title, dates and other metadata
Grayscale PDF
Convert to grayscale or black & white to save colour ink
Extract Images from PDF
Pull embedded photos out of a PDF and save as PNG or JPG
WebP to PDF
Convert WebP images to a PDF, merge many into one file
Protect PDF
Add an open password to your PDF, entirely in your browser
Unlock PDF
Remove a known password or restrictions from a PDF, in your browser
HEIC to PDF
Convert iPhone HEIC photos to PDF
AVIF to PDF
Convert AVIF images to PDF
TIFF to PDF
Convert TIFF images and scans to PDF
BMP to PDF
Convert BMP bitmap images to PDF
OCR PDF
Make a scanned PDF searchable, entirely in your browser
Redact PDF
Permanently remove sensitive text from a PDF, in your browser
Compress Image
Shrink JPEG, PNG and WebP in batch, entirely in your browser
Resize Image
Change image dimensions in batch, with presets, in your browser
PNG to JPG
Turn PNG images into JPG, batch, with the size shown before you download
JPG to PNG
Turn JPG images into PNG, batch, with optional transparent background
WebP to JPG
Turn WebP files into JPG, batch, with every frame of an animated WebP
WebP to PNG
Turn WebP into PNG with transparency intact, or knock a solid background out
Image to WebP
Turn JPG, PNG and more into WebP, batch, or hit an exact size in KB
SVG to PNG
Rasterise SVG at any size, or make a whole favicon set from one logo
AVIF to JPG
Turn AVIF images into JPG so they open anywhere, or hit an exact size in KB
Compare PDF
See exactly what changed between two PDF versions, without uploading either
SVG to JPG
Rasterise SVG to JPG at any size, and choose what colour replaces the transparency
Frequently Asked Questions
What people ask before they compare PDF files that actually matter.
Is it really free to compare PDF files here?
Yes — free, unlimited, and with no paid tier above it. There is no daily cap, no watermark, no page limit beyond the practical one described below, and no feature held back for an upgrade. The site is supported by ads, not by metering the tools.
Are my files uploaded to a server?
No. Both PDFs are read and rendered entirely on your device. The comparison happens in your browser using local code, so the documents never travel anywhere. You can verify this by opening the browser network tab while you compare PDF files, or by disconnecting from the internet after the page loads, because it keeps working.
Can I compare a PDF with a Word document?
No, and that is a deliberate limitation. Reading .docx accurately means either sending the file to a conversion server or shipping a very large parser to your browser. The first breaks the promise that files stay local; the second would slow down every page on this site. If you need cross-format comparison, a tool that converts server-side will serve you better than this one.
Can it compare PDF scans?
Visual mode works on scans immediately; text mode needs OCR first. A scan has no text layer, so there are no words to align. This tool detects that and tells you which pages are affected rather than reporting a misleading zero differences. Add a text layer with the OCR tool and both files will compare normally.
What if the two files have a different number of pages?
Extra pages are labelled as existing in only one file. Pages are paired in order, and any page beyond the shorter document is marked as present only in the original or only in the revised version. It is not forced into a pair with an unrelated page, which would flood the results with differences that are not real.
What happens if a paragraph was moved instead of edited?
It is reported as a deletion in one place and an addition in another. This version does not detect relocated content, so moving a section without changing a word still shows up as two changes rather than one. The words themselves will match exactly between the red and green blocks, which is usually enough to recognise what happened.
Can it open password-protected PDFs?
Not while the password is still on the file. An encrypted PDF cannot be parsed until it is unlocked. If you know the password, remove it first with the unlock tool, which also runs locally, and then compare PDF files as normal.
What do I do after I find the differences?
That depends on what the differences turned out to be. If a revision exposed information that should not be in the document, remove it properly with the redaction tool rather than drawing a box over it. If you are assembling a final version from parts of both files, the merge and split tools handle that without uploading anything either.
Related tools
Other things you may need before or after you compare PDF files. All of them run in your browser too.
- OCR a PDF — give a scanned document a searchable text layer so it can be compared word by word
- Redact a PDF — permanently remove sensitive text a revision exposed, rather than covering it up
- Unlock a PDF — remove a password you already know so the file can be opened and read
- Merge PDFs — assemble a final version once you have decided which parts to keep
- Split a PDF — pull out only the pages that actually changed and send those on