Free PDF Diff Checker — compare two PDFs, word by word and pixel by pixel

Built for professional comparison, not a quick glance

Two PDFs can look identical and still differ in ways that matter. This tool checks four layers at once and shows its work, so nothing slips through:

• Word-level text diff — insertions and deletions highlighted inline on every page, exactly like reviewing a code change. Not "this page changed" — these three words changed.
• Changed values — every figure, price, and percentage that changed is extracted into one table with its computed delta: $4,120,000 → $4,380,000 (+6.3%). If you're an analyst checking numbers between two versions of a report, this table is the whole job.
• Visual overlay — every page is rendered and compared pixel by pixel, then overlaid so a moved logo, a swapped chart, or a changed signature block lights up instantly.
• Metadata — page count, file size, title, author, creation and modification dates, and PDF version. A document that was silently re-generated or re-authored shows up here even when the content looks untouched.

Smart page alignment

Naive tools compare page 1 to page 1, page 2 to page 2 — so a single inserted page makes every following page read as "changed" and the comparison becomes useless. Here, pages are aligned by content similarity first: an inserted or removed page is reported as exactly that, and every other page is compared against its true counterpart, even when its position shifted. Unchanged pages are listed too, so the result is a complete audit of the document, not just the highlights.

Export the evidence

One click downloads the full change report as CSV — one row per metadata change, page change, and value change, ready for a spreadsheet or an audit file — or as JSON including the word-level diff. Individual diff overlays save as PNG. Like the comparison itself, exports are generated entirely in your browser.

Private by design

Both files are opened and rendered entirely in your browser with Mozilla's open-source pdf.js engine. Nothing is uploaded, nothing is stored, and there's no account. That makes it safe for the documents people actually need to compare — contracts, financial statements, invoices, patient records, and anything under NDA.

What people use it for

• Contract review — confirm the redline you received is the only change in a 40-page agreement.
• Finance & compliance — spot an altered figure in a statement or a re-dated filing.
• Design & print — verify a proof matches the approved artwork before it goes to press.
• Documentation — see exactly what changed between two revisions of a datasheet or manual.

The same engine that watches PDFs 24/7

This is a manual, one-off version of what Monity does automatically. Point Monity at any PDF on the web — a supplier price list, a policy document, a regulatory filing — and it checks it on a schedule, running this exact page-by-page comparison and alerting you the moment the document changes. The free plan watches 3 documents, forever.