Compare PDF online

What Compare PDF does

Compare PDF renders corresponding pages at a fixed resolution and highlights pixels whose color difference crosses a tolerance threshold.

Compare PDF runs as a queued server job after the source upload completes. The generated artifact receives a separate download link, so the original device file remains unchanged.

How to use this tool

Prepare the source
Place the earlier and later versions in a known order and remove unrelated pages that would shift the comparison. This preparation matters specifically before using Compare PDF.
Upload and inspect
Select exactly two PDF documents, wait for the Compare PDF upload to finish, and confirm that the displayed source is the intended file.
Choose the available options
Set only the Compare PDF controls needed for this output and review required fields before starting the job.
Download and verify
Inspect every highlighted region and compare it with both sources; rendering differences are not automatically content changes. Keep the source until the Compare PDF result has passed that review.

Common use cases

Prepare a delivery copy

Use Compare PDF to create a separate copy for a recipient without overwriting the maintained source.

Correct one document workflow

Apply Compare PDF to a known document problem after confirming the operation matches the intended outcome.

Create a review candidate

Generate a Compare PDF result that can be checked before it enters a records, publishing, or sharing process.

Supported inputs

exactly two PDF documents
One Compare PDF job at a time through the current public workspace

Output

One raster comparison PDF with changed pixels highlighted in magenta.

Limitations to know

Pixel comparison can flag font rendering, antialiasing, color-profile, page-size, or alignment changes and does not explain semantic meaning.
Compare PDF cannot reconstruct source information that is absent, damaged, or inaccessible in the uploaded document.
Viewer, font, image, form, signature, and accessibility behavior can change after Compare PDF; compare important output with the source.
No Compare PDF result should be treated as legal, archival, accessibility, or compliance certification without the required independent review.

Privacy and document handling

Compare PDF uploads the selected source to configured object storage so the worker can process it.
The worker attempts to remove temporary Compare PDF workspace files after the job, which is separate from stored input and output retention.
Avoid using Compare PDF with confidential material unless the published storage and retention information is suitable for the document.

Stored input and output objects are deleted automatically: files uploaded without an account are removed about 24 hours after upload, and files belonging to a signed-in account are removed after 7 days. A scheduled sweep enforces this hourly against the object store itself. Workers attempt to remove per-job temporary directories after processing. This does not delete stored input or output objects.

Read the Privacy Policy and Security page for verified implementation details and open questions.

Troubleshooting

Compare PDF cannot start

Confirm the expected exactly two PDF documents finished uploading and every required Compare PDF option contains a valid value.

Compare PDF reports a processing error

Open the source locally, remove unsupported encryption where authorized, and retry Compare PDF with a smaller valid file.

Compare PDF output is not suitable

Inspect every highlighted region and compare it with both sources; rendering differences are not automatically content changes. If it still differs, retain the source and use a workflow designed for that document feature.

Still stuck? Review Help and common questions or contact support.

Frequently asked questions

Does Compare PDF replace my original file?

No. Compare PDF creates a separate stored output and does not edit the source on your device.

Is every Compare PDF result guaranteed to look identical?

No. Compare PDF depends on the source structure and processing engine, so important pages and features must be checked.

Should I delete my source after Compare PDF?

No. Keep the source until the Compare PDF output has been opened, compared, and accepted for its intended use.

How should I check my Compare PDF result?

Open every Compare PDF download and compare it with the unchanged source before sharing or deleting anything. Pay particular attention to this documented limitation: Pixel comparison can flag font rendering, antialiasing, color-profile, page-size, or alignment changes and does not explain semantic meaning.