Compare PDF

Compare two PDF documents side by side and highlight added, removed and changed text so you can review contract or draft revisions in seconds.

Compare PDF lines up two versions of a document and highlights exactly what changed between them — additions, deletions and edited passages — so you don't have to read both files side by side line by line. It's built for reviewing contract redlines, comparing draft revisions, or checking that a signed copy matches the version that was agreed.

The tool extracts the text layer from each PDF and runs a line-by-line diff, marking inserted text and removed text with distinct highlighting. Because comparison happens in your browser, sensitive contracts and legal drafts never leave your device. Upload the original and the revised file, and scroll through a clear visual record of every change between the two versions.

How to use the Compare PDF

1. Upload the original PDF into the first slot.
2. Upload the revised or updated version into the second slot.
3. Let the tool extract and align the text from both documents.
4. Review the highlighted differences — additions and removals are marked separately.
5. Scroll or jump between changes to confirm what was edited before signing off.

Why use this tool

Line-by-line accuracy

Differences are computed on the extracted text layer, so even small wording changes in a long contract are caught rather than glossed over.

Clear visual highlighting

Insertions and deletions are marked with distinct colours, making it fast to scan a long document for the handful of clauses that actually changed.

Private by design

Both PDFs are compared locally in your browser, which matters for legal drafts and financial documents you don't want sitting on a third-party server.

Common use cases

• Reviewing redlines on a contract before signing a final version.
• Checking that a supplier's revised quote matches the terms originally discussed.
• Comparing two drafts of a policy document during an internal review cycle.
• Verifying a signed PDF matches the last agreed draft, word for word.
• Tracking edits between successive versions of a report submitted by different authors.

How the comparison works

Text is pulled from both PDFs' internal text layer and diffed the same way a code diff tool compares two versions of a file, then insertions and deletions are rendered as highlighted spans over the original layout.

Comparing scanned documents

Scanned pages are images, not text, so there's nothing for a text diff to compare. Run each scan through the PDF OCR tool first to generate a text layer, then compare the recognised output.

What it won't catch

Purely visual changes — a moved image, a different font, or a resized logo — won't show up in a text diff. This tool is aimed at wording changes, not pixel-level layout differences.

Frequently asked questions

How does PDF comparison work?

The text layer of both documents is extracted and diffed line by line, then insertions and deletions are highlighted so you can see exactly what changed between versions.

Can it compare scanned documents?

Scans contain images rather than text, so run each file through the PDF OCR tool first and compare the recognised text.

Is Compare PDF free to use?

Yes. Compare PDF on Klipza is completely free with no account, no subscription and no watermark on your files, and there is no daily usage limit.

Are my files safe when using Compare PDF?

Processing happens locally in your browser wherever technically possible, so your files are not uploaded to a server, stored or shared with third parties.

Does Compare PDF work on mobile phones?

Yes. It is fully responsive and runs in any modern browser on Android, iPhone, iPad, Windows and macOS — nothing to install.