Compare PDF Files Online for Free

Why compare two PDFs?

A colleague sends back a revised contract, or you download a new version of a report and need to know exactly what changed. Reading both documents side by side is slow, and small edits are easy to miss.

PDFly compares the text in both files directly in your browser and highlights what was added, removed, or changed — so you can review the differences instead of every page.

Common uses

Compare contract revisions
Verify requested edits were made
Check manuscript or report versions
Review updated research papers
Confirm policy or handbook changes

Best Practices & Limitations

Tips for best results

Compare the original and a re-saved/re-exported version to catch formatting drift before sending a final document.
Use this before signing an updated contract to confirm only the intended clauses changed.
For scanned documents, run OCR PDF on both files first — comparison works best on selectable text.

Limitations & when not to use this tool

Detects text and structural differences, not subtle visual-only changes like font substitution in some renderers.
Very large documents (hundreds of pages) may take longer to process since comparison runs in-browser.
Not designed for image-to-image pixel comparison — it's a text/content-level diff tool.

About compare PDF

Compare two PDF documents to identify changes between versions. This helps reviewers find additions, removals, and edits without manually checking every page.

Common uses for compare PDF

Useful for contracts, policies, reports, revisions, approvals, and document version control.

Tips for using this PDF tool

Use comparable source versions when possible and review highlighted differences in context before accepting changes.

Related PDF tools

Want a step-by-step walkthrough? Read the Compare PDF guide.

Frequently asked questions

Does it compare layout or just text?

This tool compares the readable text content word by word. Visual/layout-only changes, like font, color, or spacing, aren't detected if the underlying text is unchanged.

Can I compare scanned PDFs?

Only if they already have a text layer. Run scanned files through OCR PDF first so their text can be extracted and compared.

Will my documents be uploaded anywhere?

No. The comparison runs directly in your browser whenever possible, so your files stay on your device.

Are password-protected PDFs supported?

An encrypted or permission-restricted PDF may need to be unlocked first before it can be compared.

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Common workflow

Compare PDFExplain PDF