Yes — unlimited free, no signup. Compare PDFs is one of letsgoPDF's free differentiators alongside Smart Redact, Bates numbering, and PDF→Markdown. Runs entirely in your browser.

Do you upload my PDFs?

No. We extract the text in your browser via pdf.js and run the diff client-side. Neither file ever touches our servers. Check the Network tab in DevTools — there are no requests during a compare.

What if the PDFs have different page counts?

That's the typical case (someone added or removed a page in the new version). We concatenate the text from each PDF with [Page N] markers and run a single word-level diff over the whole thing, so a page added in the middle just shows up as a big green block — page numbers downstream still line up correctly.

Does it detect formatting changes (font, color, layout)?

No — this is a text-only diff. If you change Times to Arial without changing the words, no diff. If you bold a paragraph without changing the words, no diff. For most contract / draft / paper version-control workflows, that's actually what you want — text is what matters. Visual diff (pixel overlay) is on the roadmap.

Will it work on scanned PDFs?

No — scanned PDFs are images, not text. Run OCR first (PDF tools → OCR), save the text-based PDF, then come back to compare.

What's the granularity? Word-level, character-level, line-level?

Word-level. Line-level misses small wording changes ("shall" vs "may"). Character-level produces unreadable confetti when whole sentences move. Word-level is what Word's Track Changes and Google Docs revision history use — it's the right granularity for human review.

Can I download the diff?

Yes. Click Download diff (.md). Removed words come out as ~~strikethrough~~, added words as **bold**. Render in GitHub PRs, Notion, Obsidian, or any Markdown editor.

FREE · IN-BROWSER · NO UPLOAD

Compare two PDFs. See exactly what changed.

Drop a contract v1 and v2, a draft and a final, or any two PDF documents. Get a word-level diff with red strikethrough on removed text and green highlight on additions. Toggle between full document, only-changes, only-added, only-removed views. Download the diff as Markdown for GitHub PRs, Notion, Obsidian, or email. 100% in your browser — neither PDF ever leaves your device.

Compare two PDFs All PDF tools

How it works

Drop two PDFs onto letsgoPDF. pdf.js extracts the text from each in your browser — no upload.
Click Compare. Word-level diff runs client-side; results render in under a second for typical contracts.
Review: stats up top (X added, Y removed, Z unchanged), then the diff inline. Toggle Only changes to skip past unchanged regions. Only added shows just the new text; Only removed shows what's gone.
Click Download diff (.md) for a portable Markdown file. ~~strikethrough~~ for removed, **bold** for added — renders in any Markdown tool.

Who's this for?

Lawyers + paralegals. Compare contract drafts side by side. Word-level diff catches a "shall" → "may" or "30 days" → "60 days" instantly. Cheaper than Draftable, faster than Word's compare on a multi-hundred-page contract.
Technical writers + product managers. Diff spec versions, release notes drafts, design doc revisions. Much more readable than tracking changes in Word.
Researchers + grad students. See what your advisor changed in the latest draft. Compare a paper's v1 and v2 before submission.
Compliance + audit. Verify that a vendor's "minor edits" to a policy doc are actually minor.
Anyone who's ever asked "what did they change?" while staring at two near-identical PDFs.

Why letsgoPDF for PDF compare

No upload. Compare runs in your browser. The PDF you're comparing is probably sensitive — a contract, a draft, an internal doc. We don't want it on our servers either. Verify in DevTools' Network tab: zero outbound requests.
Word-level granularity. Same level Word's Track Changes and Google Docs revision history use — readable for humans. Line-level (the lazy version) misses small wording changes; character-level is unreadable confetti.
Unified or filtered views. Skip unchanged regions when the document is mostly identical. See only additions if you're a reviewer; only removals if you're checking what got cut.
Markdown export. Diff goes into your existing tools — GitHub PR descriptions, Notion pages, Obsidian notes, email — instead of being trapped in a PDF reader.
Same toolkit. Need to OCR a scanned old version first? Compress before sending? Redact sensitive bits before sharing the diff? letsgoPDF has all of it.

Common questions

Is this really free?: Yes — unlimited free, no signup. Compare is part of the free differentiators set (alongside Smart Redact, Bates, PDF→Markdown). Runs entirely in your browser.
How big can the PDFs be?: Practical limit is around 100 pages each on a typical laptop — at that size compare runs in under 2 seconds. Bigger documents work too, just slower. If your browser tab gets sluggish, split first (PDF tools → Split) and compare each chapter separately.
What if the page numbers don't match?: Common case — someone added a page in the middle of v2. We don't try to align pages 1-to-1 (that breaks badly when pages move around). Instead we concatenate text with [Page N] markers and run a single text diff over the whole document. The result reads naturally and page markers stay accurate.
Does it pick up formatting changes?: No — this is text-only. If you bold a sentence without changing words, no diff appears. For most version-control workflows that's actually what you want; text is what matters in contracts, drafts, and policy docs. Visual / pixel-level diff is a different feature (on the roadmap).
Can I compare a PDF to a Word document?: Convert the Word doc to PDF first (PDF tools → To PDF, free for the conversion step), then compare. Same flow works for PowerPoint or Excel — convert, then compare.
What's the diff library?: diff (the npm package, jsdiff) running word-level. Open source, well-tested, used by GitHub itself in places.

Other free PDF tools

Compare two PDFs now