Compare two PDF versions and review the visible changes
Updated · WaterPDF
Compare original and revised PDFs on your device. Review visual highlights, available text and page changes, then save a comparison report.
No signup · Local file processing
Choose the original and revised versions
Use clear filenames so the two versions are not confused. Choose each PDF in its labeled input, up to 50 MB and 20 pages per document. Both must be readable without an opening password; unlock a copy first when needed. Comparison creates a separate review result and does not overwrite either source.
Review the documents page by page
The tool compares pages at the same position in each document. Review the original, revised and highlighted comparison for each page. Added or removed pages and page-size changes are identified. Inserting a page can shift later comparisons, so a large set of highlights does not necessarily mean all those words were edited.
Use sensitivity to manage visual noise
Font rendering, antialiasing, page shifts and scan noise can appear as differences. Adjust sensitivity and inspect both source images when a highlight looks surprising. The comparison uses a bounded rendering resolution; very small, faint or low-contrast changes can be missed. A highlight count is not a count of meaningful document edits.
Read the available text summary alongside the images
Selectable-text summaries can help you notice wording changes, but PDF reading order can differ in tables and columns. A scan without a text layer has only visual comparison. Run OCR separately if you need recognized words, and check that recognition first; comparing OCR errors as if they were real edits can be misleading.
Download a report for your review
Save the PDF report with its summary and side-by-side page pictures, or the plain text summary with bounded difference excerpts. The report is not a new editable copy of the originals. Keep both source files with it so another reviewer can inspect the actual documents. It is not a legal redline, a certificate-signature check or proof that hidden content and metadata are identical.
Choose the next document task after checking
If a field value is wrong, reopen the editable form in Fill PDF forms. Use PDF to text when you need to reuse existing selectable wording. Split PDF can reduce a long document to the pages relevant to a review. Apply an opening password only after finishing edits and confirming the final version.
Interpret a comparison carefully
| What you notice | Possible cause | What to check |
|---|---|---|
| One amount is highlighted | A value or its rendering changed | Read the amount in both original pages |
| Most later pages are different | An inserted page shifted page positions | Check page order and added-page markers |
| Many tiny edge highlights | Font or scan rendering noise | Adjust sensitivity and inspect the source |
| No selectable-text summary | The page may be a scan | Use visual review or run OCR separately |
A clean comparison is not proof of legal, metadata or hidden-content equivalence.