Two versions of the same document, and you need to know exactly what changed. A compare PDF check does the detective work: upload the original and the revised file to see them side by side with synchronized scrolling, or run a word-by-word text diff that highlights every removed and added word in red and green, with per-page change counts.
This free compare pdf tool offers two views. Visual mode renders both PDFs page by page for layout, image, and formatting checks. Text-diff mode extracts the actual words and compares the first 30 pages in detail. Everything runs in your browser — your confidential contracts, legal drafts, and manuscripts are never uploaded, there is no signup, and there is no watermark.
Compare PDF Files Side by Side
Spot every difference between two PDF versions — visually with synced scrolling, or as a highlighted word-by-word text diff.
Drop the original PDF here
or use the button below
Drop the revised PDF here
or use the button below
File A
File B
How it works: visual mode renders both PDFs page by page for eyeball comparison with synchronized scrolling. Text-diff mode extracts the words from each page and highlights exactly what was removed (red) and added (green) — something most online comparers cannot do.
🔒 100% private — your files never leave your device. Comparison happens entirely in your browser.
- This compare PDF tool shows two PDF versions side by side with synchronized scrolling, plus a word-by-word text diff.
- Deletions appear in red, insertions in green, with per-page change counts so you can jump to what changed.
- Text diff covers the first 30 pages; visual mode handles documents of any length.
- Both files stay in your browser’s memory — nothing is ever uploaded, so confidential contracts are safe.
- Image-only scans have no words to diff — run them through OCR first for text comparison.
How to Compare Two PDF Files for Differences
- Upload both files. Drop the original as File A and the revised version as File B — or click each zone to browse. Use the swap button if you mix them up.
- Press Compare files. Both PDFs are rendered and their text is extracted, with a progress bar keeping you informed.
- Start in visual mode. Scroll either pane — the other follows automatically. Use Prev/Next or the zoom control to inspect pages closely.
- Switch to text diff. Pick a page from the dropdown (each shows its change count) and review red removals and green additions word by word.
- Check the summary. The result line tells you how many pages changed and flags any page-count mismatch between the files.
Because everything is computed locally, this compare pdf tool handles even confidential documents safely — a major advantage over upload-based comparers when you are reviewing sensitive material.
Compare PDF Files Side by Side: Visual vs Text Diff
Visual side-by-side is for seeing: changed layouts, moved images, new charts, altered formatting, and reflowed paragraphs. Both documents render at the same zoom, and synchronized scrolling keeps the same region in view — invaluable when pagination shifted and page 12 of version A is now page 14 of version B. Text diff is for reading: it extracts the words from each page and aligns them, painting deleted words red with strikethrough and added words green. A contract clause that changed shall to may jumps out instantly. The two views of this compare pdf tool complement each other — use visual mode to find where something moved, text diff to see exactly what the new wording is. Professional desktop suites like Adobe Acrobat Pro offer a similar Compare Files workflow, and the text-diff approach descends from the classic diff utilities that compare files line by line — but this free compare pdf tool does it in your browser without a paid license or an upload.
Features That Set This Tool Apart
- Synced side-by-side viewers. Scroll one pane and the other follows proportionally; page navigation jumps both panes together.
- Word-level text diff. A real diffing algorithm highlights exactly which words were removed and added — most free comparers only show pages visually.
- Per-page change counts. The page dropdown lists every page with its added/removed totals, so you can jump straight to the pages that changed.
- Zoom control. Inspect fine print at 70%, 100%, or 140% without losing sync between the panes.
- Page-count mismatch detection. If one file has extra pages, the summary says so — silently added or deleted pages cannot hide.
- Swap button. One click reverses A and B if you uploaded them in the wrong order.
- 100% private. Both PDFs stay in your browser’s memory; rendering, text extraction, and diffing never touch a server.
Reading the Diff Results
The summary line at the top of the results tells you the big picture: how many of the compared pages contain text changes, and whether the files have different page counts. A page-count mismatch is itself a finding — it means pages were added or removed, not just edited.
In text-diff mode, each page option shows its change count up front, with the added and removed breakdown. Pages with zero changes need no review, so a long document usually narrows to a handful of pages worth reading. Within a page, red strikethrough marks words present in the original but gone from the revision; green marks words the revision added. Unchanged words appear as plain text so the sentence context stays readable. If a page was rewritten so heavily that word-by-word alignment becomes meaningless, the tool says so instead of showing a misleading diff — check such pages in visual mode. The text diff analyzes the first 30 pages in detail; beyond that, visual mode with synced scrolling covers the rest of the document.
When Comparing PDF Versions Matters Most
Any time two versions of a document exist, it pays to compare PDF files before you sign, send, or publish.
Contract review. Verify that the signed version matches the negotiated draft — every changed word highlighted, nothing trusted to memory. This is the classic blackline use case, done free in your browser.
Legal and compliance drafts. Track revisions across redlines without expensive desktop software.
Manuscripts and theses. See what your editor actually changed between revisions, page by page.
Invoices and statements. Confirm that a reissued document differs only where it should.
Design proofing. Compare exported PDFs visually to catch shifted elements before print.
Scanned document versions. For image-only scans, run them through our OCR PDF tool first so the text diff has real words to work with. And once a contract version is final, you can move on to our Sign PDF tool to finalize it — no printing required.
Tips for Accurate PDF Comparisons
Compare PDF pairs early in a review cycle — catching a wording change in draft two beats catching it after signing.
Compare the right pair. The diff is only as meaningful as the versions you feed it — double-check that File A is truly the older version.
Start with the change counts. The page dropdown’s per-page totals tell you where to look; a 40-page contract may only have changes on 3 pages.
Remember scanned PDFs have no text. The text diff needs extractable words. Image-only scans will show as empty — OCR them first.
Watch for reflow. One inserted paragraph can shift all following text; the visual view shows the new pagination while the diff shows the actual edits.
Use zoom for fine print. Footnotes and captions are where sneaky changes hide — 140% zoom makes them readable.
Do a final page-count check. Before signing off, confirm the summary line reports the page counts you expect — added or removed pages are the easiest change to miss.
Compare PDF: Frequently Asked Questions
How do I compare two PDF files for differences?
Upload the original document as File A and the revised version as File B, then press Compare. Visual mode shows both PDFs side by side with synchronized scrolling, so you can eyeball layout and formatting changes. Switch to text-diff mode to see exactly which words were removed or added on each page, highlighted in red and green with per-page change counts and a summary of how many pages contain text changes.
What is the difference between visual comparison and text diff mode?
Visual mode renders both PDFs page by page so you can compare layout, images, fonts, and formatting — scrolling one pane automatically moves the other. Text-diff mode extracts the actual words from each page and runs a word-by-word comparison, marking deletions in red and insertions in green. Use visual mode to catch design and formatting changes, and text diff for contract, policy, or manuscript revisions where the exact wording is what matters.
Can I compare PDFs without uploading them to a server?
Yes. Both PDFs load directly into your browser’s memory, and the rendering, text extraction, and diffing all happen locally with JavaScript. Nothing is ever sent to any server, so there is no upload queue and no copy of your documents sitting on a stranger’s machine. That makes this compare PDF tool safe for confidential contracts, legal drafts, board papers, and unreleased manuscripts that must never leave your device.
Can this tool replace legal blackline comparison software?
For many review workflows, yes. Law firms traditionally use blackline software to spot wording changes between contract drafts — this compare pdf tool’s text-diff mode does the same job, highlighting every added and removed word side by side. It runs in a browser instead of a paid desktop suite, and it never uploads your documents. Keep in mind that dedicated legal tools add redlining exports and audit trails; this free tool focuses on fast, accurate change detection you can review immediately.
Do scanned PDFs work with text-diff mode?
Only if the scanned PDF has a real text layer. Text diff compares extracted words, so image-only scans have no words to extract and will show no meaningful differences — visual mode still works fine for those. The fix is simple: run the scan through an OCR tool first to add a text layer, then compare the OCRed copies. Our free OCR PDF tool does exactly that in your browser, and afterwards the word-by-word comparison works normally.
Related Free Tools
- OCR PDF — make scanned PDFs searchable before comparing them.
- Sign PDF — sign the final version once your comparison is done.
- Scan to PDF — digitize paper documents with your phone camera.
- Redact PDF — permanently remove sensitive text before sharing.
- Text to PDF Generator — turn typed or pasted text into a PDF.