How to compare two PDFs
- Drop the original on the left and the changed version on the right.
- Click Compare PDFs. Both documents render and are compared page by page.
- Review the differences. Each page shows original · changed · differences, with changed areas in red, plus a summary of which pages differ.
A visual diff that catches everything
Comparing two versions of a contract, a design, or a report by eye is slow and error-prone — a moved paragraph or a changed number is easy to miss. Sleek PDF renders both PDFs and overlays them pixel-for-pixel, so anything that changed the appearance of a page lights up in red. Because it's visual rather than text-based, it works on scans and image-heavy PDFs too, and because it runs in your browser, you can compare confidential drafts without uploading them anywhere.
Common uses for comparing PDFs
- Compare contract versions — spot every change between two drafts of an agreement.
- Check a proof — confirm a revised design or layout matches what you expected.
- Find edits in a report — see exactly what changed between two versions of a document.
Frequently asked questions
How do I compare two PDFs and see what changed?
Drop the original PDF on the left and the changed one on the right, then click Compare. Sleek PDF renders both and shows each page side by side with a third “Differences” image where every changed area is highlighted in red, plus a summary of which pages differ.
Does it compare the look of the pages or the text?
It's a visual (pixel) comparison — it catches anything that changed how a page looks: edited text, moved images, new stamps, layout shifts, colour changes. That makes it reliable even for scanned or image-based PDFs where text extraction wouldn't help.
What if the two files have a different number of pages?
Pages that exist in only one file are flagged as added or removed, so you can see where content was inserted or deleted.
Is there a page limit?
Comparison renders both documents in full, so it's capped at the first 30 pages to keep memory reasonable. For longer documents, split them into sections first.
Are my PDFs uploaded to compare them?
No. Both files are rendered and compared entirely in your browser — neither leaves your device. That matters for comparing drafts of contracts or agreements.