What does Compare PDF do?
Compare PDF is a free online tool that can generate a visible diff image between two PDF files (first page). The PNG result from Compare PDF is a separate copy to inspect before you use it elsewhere. One possible use is cover-page revisions checked before publication.
PDF check renders the first page of each of two PDFs and makes a visible difference image. It can reveal a changed heading, shifted layout or replaced diagram on that page.
The result is a PNG rather than a marked-up PDF or a textual list of changes. Use sources with similar page width and height and angle so that differences in framing do not overwhelm the differences you want to check.
Two scans of the same sheet can differ in position or brightness. That can create marks without a change in wording.
Align the sources in your own editor if framing dominates the result. A changed first page says nothing about page two. Use an extract to examine another page separately.
Compare two PDF first pages online: steps
Before using Compare PDF, decide what the new copy must contain and where it will be used. Upload the two versions to compare, placing the earlier version first and the later version second. Review the upload area and all values required by the current Compare PDF form.
Choose the source
Look at the invoice amount in both source files. For Compare PDF, add the required sources in the intended input order. Keep a source copy for another attempt.
Review the form values
The Compare PDF form has no extra task settings. Check the source in the file area.
Run the file task
Use Process Compare PDF after checking the source and form values. Wait for the job to finish. An error means this attempt failed.
Save and check the output
Check the difference image alongside both original first pages to interpret changed regions. Store the output on your device. Name this copy separately from the original.
Visual diff: uses for Compare PDF
Compare PDF can help with first-page invoice layout changes inspected. It can also be used for single-page proofs compared during design review. The PNG result from Compare PDF must suit the intended reading or editing step, so keep the source until that check is complete.
- Cover-page revisions checked before publication.
- First-page invoice layout changes inspected.
- Single-page proofs compared during design review.
- First-slide exports checked for unexpected visible shifts.
Formats and limits for Compare PDF
The Compare PDF form accepts PDF sources. Each Compare PDF upload can be up to 300 MB, which equals 300 MiB. The allowed suffixes on the Compare PDF page do not prove that a source has valid content inside it.
| Accepted formats | Maximum file size | Output |
|---|---|---|
| 300 MB per file (300 MiB upload limit) | PNG |
Only the first page is compared. This is not a whole-file audit, and a blank-looking result cannot prove that later pages are identical.
How this tool works
Compare PDF uses ImageMagick and Poppler to handle the source on the server. The Compare PDF request uses your chosen input rather than any local editing project left on your device. Check the PNG contents produced by Compare PDF before treating them as ready for another app or reader.
For Compare PDF, your browser uploads the source to our file-processing server. This is a server task, not local editing.
Files are due for deletion within 1 hour. Cleanup runs during normal service operation. Keep a local download for future use.
Compare PDF questions and answers
If Compare PDF gives an unexpected result, start by checking the source type and the values used in the form. Check the PNG contents from Compare PDF as well as the filename or displayed message. For another result type, compare Compare PDF with the separate tools described in these answers.
What matters when using Compare PDF?
Distinguish moved objects from changed text on a proof. View that area at its intended display size. Note any differences that affect your purpose.
Why try Extract PDF Pages?
Extract PDF Pages offers another task beside Compare PDF: extract specific pages to a new PDF. Extract PDF Pages returns PDF. The stated PNG output from Compare PDF is not a listed input type for Extract PDF Pages.
Why try PDF to PNG?
PDF to PNG offers another task beside Compare PDF: convert all PDF pages to PNG images (zipped). PDF to PNG returns ZIP. The stated PNG output from Compare PDF is not a listed input type for PDF to PNG.
Why try PDF to JPG?
PDF to JPG offers another task beside Compare PDF: convert all PDF pages to JPG images (zipped). PDF to JPG returns ZIP. The stated PNG output from Compare PDF is not a listed input type for PDF to JPG.
What if my PNG result does not open?
For a failed Compare PDF result, first confirm that the download completed and that the viewer supports PNG. Try another local viewer for that format.
Record any error message for support. Keep private source material out of the report.
How do I report a problem with Compare PDF?
Contact support with the Compare PDF page name, source format and the error you saw. Mention any relevant form settings you chose. Do not send passwords or private attachments.