How to Compare Two PDF Files and Find Changes

To find what changed between two versions of a PDF, open Compare PDF, add the original as File A and the new version as File B, and click Run Text Comparison. Every word removed from the original is highlighted in red and every word added in green, with an overall similarity score — so a changed clause in a 40-page contract can't slip past you.

Compare two PDFs step by step

1. Open Compare PDF.
2. Add the original document as File A.
3. Add the changed version as File B.
4. Click Run Text Comparison.
5. Read through the highlighted result: red text was in the original but is gone; green text is new. The similarity percentage tells you how much changed overall.

When comparing matters

• Contracts: the other side sends back "the same contract with your comments addressed". Comparing shows whether anything else changed — a liability cap, a notice period, a payment term.
• Policies and terms: see exactly what an updated privacy policy or terms of service changed.
• Price lists and quotes: catch quietly increased prices between two versions.
• Reports and papers: check what a co-author edited, or what changed between draft and final.
• Forms and applications: make sure a resubmitted document only changed what was requested.

How to read the result

• Red (deleted): text in File A that isn't in File B.
• Green (added): text in File B that isn't in File A.
• A red word followed by a green word usually means a replacement: "30 days" became "14 days".
• Similarity: 100% means the text is identical. A high score with a few highlights means small edits; a low score means substantial rewriting, or that the documents are laid out very differently.

Small changes in numbers, dates and names are the easiest to miss by eye and the most important to catch, so scan specifically for short highlights.

What the comparison looks at

It compares the text of the two documents, not their appearance. That means:

• Changed wording, numbers and punctuation are found.
• Formatting changes — fonts, colours, bold, layout — aren't flagged, since the words are the same.
• Images and charts aren't compared.
• Text that moved to a different place shows as deleted in one place and added in another.

Scanned documents

A scanned PDF is a picture with no text in it, so there's nothing to compare. Turn scans into text first with PDF OCR. OCR isn't perfect, so expect a few false differences where letters were misread — check those against the scan.

Want the raw text instead?

If you'd rather compare in your own way — in a text editor with a diff feature, or by pasting into a spreadsheet — extract the text of each version with PDF to Text. Choose Original lines so both versions break lines the same way.

Tips for cleaner comparisons

• Compare like with like. Two exports of the same document compare cleanly; a Word export against a scanned printout produces a lot of noise.
• Compare the relevant part. If only one section matters, extract those pages from both versions first with Split PDF.
• Need to edit the result? Convert the newer version to Word with PDF to Word and use Word's own review tools.

Frequently asked questions

Are my documents uploaded?

No. Both PDFs are read and compared in your browser, which matters for confidential contracts and drafts.

Can I compare a Word document with a PDF?

Convert the Word document to PDF first (in Word, File › Save As › PDF), then compare the two PDFs.

Why does it show changes I didn't make?

Different software can break lines and hyphenate words differently, which shows up as small differences. They're usually obvious — a hyphen here, a line break there — and can be ignored.