What Compare PDF changes inside the PDF
Check whether two PDFs say the same thing when you cannot see a visual diff.
Upload exactly two PDFs. The tool compares their extractable text and gives you a short PDF report.
Where this falls short
Scanned pages with no text layer look empty, so two different scans can look identical. This is not a side-by-side visual comparison.
A related step, if you still need one, is Compress PDF.
When Compare PDF is the right page
Compare PDF sits on this site because PDF and PDF are not interchangeable, even when they look similar in a file list. Check whether two PDFs say the same thing when you cannot see a visual diff. Application portals, email, and print shops still ask for PDF in 2026, often with a size cap. Application portals, email, and print shops still ask for PDF in 2026, often with a size cap.
Upload exactly two PDFs. The tool compares their extractable text and gives you a short PDF report.
What you give up by leaving PDF
PDF keeps a page looking stable on most screens. It is the file offices send when the reader should not casually reflow the layout. A scan or a photo of a page has no text layer until OCR runs, and OCR is only as good as the image.
Keep the PDF if anyone might need the original page look, because extracts drop columns and images.
What you gain, and do not gain, with PDF
Compare PDF keeps the format family as PDF and still changes the file you can use. Application portals, email, and print shops still ask for PDF in 2026, often with a size cap. A PDF exported from Word or a browser usually has a text layer, so the words can be copied.
Converting a PDF does not improve a blurry scan, and a text extract is not the designed page.
A test that matches the real file
Start from the question the other software asked. If it asked for PDF, Compare PDF is the matching page. If it asked for something else, switch tools instead of hoping a similar extension will pass. Check whether two PDFs say the same thing when you cannot see a visual diff. Upload exactly two PDFs. The tool compares their extractable text and gives you a short PDF report. The limit is the part people skip, and it is the part that decides whether the download is usable. Scanned pages with no text layer look empty, so two different scans can look identical. This is not a side-by-side visual comparison. The file stays in your browser and is not uploaded. The limit is 100 MB. Keep the original until the download has been opened in the program that will use it. Check three things in the download: it opens, the PDF material you cared about is still there, and the file size or the layout is what the form described. A new extension alone is not those three things. If a portal, a teacher, or a client rejects the file, send them the original PDF as well when you are allowed to. Compare PDF is a convenience copy. It is not a new master. A PDF page can be text, a scan, or a picture of a design. Compare PDF does one of those jobs, not all of them. If you needed editable sentences, a text extract is the right family. If you needed the page to look identical, send the PDF or export from the app that built it. Open the download before you throw away the original.
Here is the decision for Compare PDF. You start with PDF and you stop when a real program accepts PDF. A PDF exported from Word or a browser usually has a text layer, so the words can be copied. A scan or a photo of a page has no text layer until OCR runs, and OCR is only as good as the image. If those two sentences describe a tradeoff you do not want, do not convert. Renaming the extension by hand will not do this job. Running the tool twice on its own output will not do it either.
Scanned pages with no text layer look empty, so two different scans can look identical. This is not a side-by-side visual comparison.
A related step, if you still need one, is Compress PDF.
Other jobs start from the homepage, where each tool is named for the conversion it actually does.