How to Compare Two PDFs

Quick answer: Compare two PDF versions side by side and get a page-by-page list of added, removed, and changed text. Open PDF 比较 — everything runs locally in your browser, and files never leave your device.

Steps

1. Upload the old and new versions to the PDF Compare tool.
2. Read the per-page diff: deletions, insertions, and modifications are listed separately.
3. Export or screenshot the report for review records.

Important notes

• Comparison runs on the text layer — a scanned version must go through OCR first, or every page shows as "different".
• Layout changes (font, spacing) are ignored; only wording counts.
• Misaligned starting pages shift the whole diff — both files should begin at the same content point.

Common questions

Does it compare tables? Table cell text participates; structural changes like merged cells are not flagged separately.

Can I compare three versions? Two at a time — chain v1→v2→v3 for multi-version review.

Pro tips

Structure the comparison like a review, not a glance: run the tool for the mechanical diff, then triage its findings into three buckets — content changes (the words), numeric changes (amounts, dates, clause numbers — verify each against intent), and noise (whitespace, reflow artifacts the diff flags but no human would call a change). For contracts, the numeric bucket deserves its own pass because a changed digit is the highest-consequence, lowest-visibility edit. Save the diff report with the document; "what changed between v3 and v4" is a question someone will ask again.

Why does the diff show changes I cannot see? Invisible characters, spacing differences, or reordered words with identical visual result — the diff is textual, and text differs more than pixels do.