How to Compare Two PDF Files for Differences

When someone sends back a revised contract, lease, policy or report, the important question is what changed. Changes are not always highlighted, and even when a summary is provided, it may not mention every edit. Reading two long documents side by side is slow and easy to get wrong. A comparison tool shows every text difference in seconds.

Compare PDF runs in your browser, so neither document is uploaded. That matters for contracts and other confidential material.

1. Open Compare PDF.
2. Add the older version as the original (A) and the newer version as the revised document (B).
3. Enter passwords for any protected PDFs.
4. Run the comparison.
5. Review the side-by-side results. Text only in A has been removed; text only in B has been added.

Compare PDF extracts the readable text from both documents and compares it. It finds added, removed and changed words, sentences and paragraphs, including small but important edits such as a changed number, date, name or a single word like may becoming must.

Because the comparison works on text, some kinds of change are outside its scope.

• Formatting changes such as bold, font or color.
• Layout changes where text moved position but the wording stayed the same.
• Changes to images, logos, charts and signatures.
• Scanned documents, which contain images of text rather than text. Both PDFs need selectable text.

A comparison makes reviewing faster, but you still need to read the changes in context.

• Always put the version you agreed to, or last sent, in A and the new version in B.
• Pay close attention to numbers, dates, parties, notice periods, liability limits and termination clauses.
• Check that every change matches what was discussed or summarised by the other party.
• Keep both versions and note the date of each, so you know which one you compared.

To respond with your own changes, convert the document with PDF to Word and use tracked changes, or make small corrections directly with Edit PDF. When you receive the next version, compare it with your last copy again.