Compare two PDFs
See exactly which lines differ between two PDFs. Both files stay on your device.
- Runs on your device — the file is never sent anywhere
- No sign-up, no watermarks, no daily quotas
- Free, with no limit on how often you use it
How it works
Two versions of a contract, a policy or a specification, and nobody can remember what moved. Reading them side by side is how mistakes get missed. This extracts the text from both and reports precisely which lines were added, removed or left alone — which is usually a far shorter list than it feels like.
How the comparison works
The text is pulled from both documents, then compared using a longest-common-subsequence diff — the same approach version control uses. That matters: a naive comparison that simply lines up the files position by position reports every line after an insertion as changed, which makes the report useless. This one identifies the insertion and leaves the rest alone.
Line by line or word by word
Line by line is the right default for documents whose paragraphs stay put. Word by word is better when text has reflowed — a sentence added early in a paragraph shifts every line after it, so a line comparison exaggerates the change while a word comparison shows the handful of words that actually differ.
Whitespace
By default, differences in spacing are ignored, because a PDF's text extraction often produces slightly different spacing for text that reads identically. Turn that off if you are comparing something where spacing is meaningful, such as code or a formatted table.
What it cannot see
It compares text, and only text. A change to a font, a colour, an image, a signature, a logo or the page layout is invisible to it — as is a change to a scanned page, which contains a picture of words rather than words. If neither file has selectable text, the tool says so rather than reporting that nothing changed. Run scans through the OCR tool first.
Why this stays on your device
The documents people most want to compare are the ones they can least afford to upload: contracts under negotiation, drafts under NDA, medical and legal paperwork. Both files are read in the page with the browser's own PDF engine and the report is generated there.
Compare two PDFs — questions
Does it show changes visually, side by side?
No. It produces a text report marking each differing line with - for the first file and + for the second. That format is precise and easy to search, but it is not a visual overlay of the two pages.
Can it compare scanned PDFs?
Not directly — a scan holds an image, not text. Run each file through the scanned-PDF OCR tool first, then compare the results.
Will it spot a changed image or signature?
No. Only text is compared, and the page says so rather than letting you assume otherwise.
How large can the files be?
Large files work, but a word-by-word comparison of two very long documents needs a lot of memory; the tool will tell you to switch to line-by-line if it would be too much.
Are the files uploaded?
No. Both are read on your device and the comparison happens there.