A PDF diff tool compares two PDF files and highlights every change automatically — like a spell checker, but for differences between document versions. Here's the fastest way to use one for free.
A PDF diff tool renders both documents as images and compares them pixel by pixel. Any pixel that is different between the two versions is highlighted — usually in red — making changes immediately visible without manual reading.
Go to pdfeditor.onl/compare-pdf. Upload your two PDFs (File A = original, File B = revised). Click Compare. The diff runs entirely in your browser — your documents are never uploaded to any server.
Tip: Use Diff view for the clearest visual result — changed pixels appear in red on a greyscale background, making even small text edits immediately obvious.
Click Download Page X for a single-page PNG diff, or Download All Pages as PDF to get all diff pages bundled into one report file.
Yes — pdfeditor.onl/compare-pdf runs entirely in your browser using WebAssembly. Files are never uploaded to any server.
Very accurate. The tool renders pages at high resolution and compares every pixel. Even a single changed character in a paragraph is detected.
Yes. There is no artificial page or file size limit. Processing time depends on your device speed.