Compare PDF shows what changed between two versions of a PDF. Text differences lines the two documents up side by side and highlights the changed words inside each changed line. Visual overlay renders every page of both files and marks the pixels that differ in red and green. Both PDFs are compared in your browser and never uploaded.
How to compare two PDFs
- Click Choose the first PDF and pick the original version.
- Click Choose the second PDF and pick the changed version.
- Pick Text differences or Visual overlay, set the options, and click Compare.
- For a text comparison, click Download report to save the differences as a text file.
Two ways to compare
| Text differences | Visual overlay | |
|---|---|---|
| Compares | The text of each page | Each page as a picture |
| Shows | Changed, added and removed lines side by side, changed words highlighted | Red where only the original has ink, green where only the changed PDF has it, grey where both match |
| Works on scans | No | Yes |
| Catches layout and picture changes | No | Yes |
| Summary | Count of changed, added and removed lines | Per page: “differences on x% of the page” |
| Report | Download as text | On screen |
Text differences
The text of both PDFs is read page by page, with a page marker before each page, so you can see where a change sits. The comparison then aligns the two texts and shows them side by side:
- Changed lines appear on both sides, with the exact words that differ highlighted.
- Added lines appear only on the right, removed lines only on the left.
- Ignore spacing and line breaks inside paragraphs joins the lines of each paragraph and treats runs of spaces as one, so a paragraph that only wraps differently, or has an extra space, is not reported as changed.
- Show only changes hides the lines that are the same, which makes long documents quick to review.
This is the mode for reviewing a revised contract, a new version of terms and conditions, an updated report or an edited manuscript, where every changed word matters.
Visual overlay
Each page of both PDFs is rendered and laid on top of its counterpart, page 1 on page 1, page 2 on page 2 and so on. Everything that matches is shown in light grey. Ink that is only in the original is red, ink that is only in the changed PDF is green. Under each page you see a short note: no visible difference, differences on a given share of the page, or that the page only exists in one of the files.
Use it for scans, drawings, plans, brochures and forms, or to confirm that two exports of the same document really look the same.
Pages are compared by number. If a page was added or removed near the start, every later page shifts and shows as different. In that case the text mode gives the clearer picture, or take out the extra page with Split PDF first.
Good to know
- Password-protected PDFs need to be unlocked first with Unlock PDF, if you know the password.
- If neither PDF has text (both are scans), the text mode tells you so; switch to Visual overlay.
- To compare scans by their words, make them searchable first with OCR PDF, then use Text differences.
- Large PDFs take longer in visual mode, as each page is rendered twice.
Related tools
- Mark the changes you found with Highlight PDF, or fix them with Edit PDF.
- Get the full text of a PDF with PDF to Text.
- Put the new version together with an appendix using Merge PDF.
Private by design
Your files are processed on your own device and never uploaded. See how it works.