Compare PDFs

PDF is the format text tends to come back in: the publisher's typeset proof, the signed contract, the paper as the journal printed it. In Verso, you drop both versions and read what changed side by side, word by word, without converting anything first.

PDF with PDF, or PDF with Word

Both versions can be PDFs, or one can be a PDF and the other a .docx, .odt, .txt or .md. Comparing the PDF with the source file is how you check that nothing changed along the way:

• the typeset proof against the manuscript you handed to the publisher;
• the signed PDF contract against the last Word draft;
• the published paper against the version the reviewers accepted.

What Verso does with the PDF before comparing

A PDF doesn't store paragraphs, only letters with a position on the page. Before comparing, Verso rebuilds the text:

• it joins the lines back into paragraphs;
• it drops headers, footers and page numbers, which aren't text changes;
• it rejoins words the layout split with a hyphen at the end of a line.

That's why a PDF comparison is a reconstruction, and the screen says so. In our tests, in a 99-page book, 895 of the 900 paragraphs came back whole. When you have the word processor's file, it gives the most exact result.

Scanned PDFs

A PDF that came out of a scanner is an image of a page, with no text inside. Verso doesn't do OCR, and tells you when it finds no text. Run the file through an OCR program first and compare the result.

Without uploading the PDF anywhere

Many sites that compare PDFs ask you to upload both files to their server. In Verso, the PDF is read by Mozilla's pdf.js inside your browser, and the comparison happens there too. No file leaves your computer, which matters when the PDF is a contract or an unpublished manuscript. For legal documents, see also compare contracts.