Question 1

Are my documents uploaded anywhere?

Accepted Answer

No. Files are read by the browser and stay in the tab's memory. The app makes no network request after the page has loaded — no uploads, no analytics, no fonts from a CDN. You can verify it by opening DevTools' Network tab, or by switching the network off and using it anyway.

Question 2

Which file formats can it compare?

Accepted Answer

PDF, Word (.docx), OpenDocument Text (.odt), plain text and Markdown — in any combination, because only the text is compared. Legacy .doc and .rtf are not supported; save them as .docx first.

Question 3

Can it compare scanned PDFs?

Accepted Answer

No. A scan is a picture of text and has no text layer to compare. redline detects this and says so rather than showing an empty comparison; there is no OCR.

Question 4

How does it handle tracked changes?

Accepted Answer

A .docx or .odt that still carries revision marks is compared as if every change had been accepted: insertions kept, deletions dropped. The app says which side had revision marks.

Question 5

Does it work offline?

Accepted Answer

Yes. It installs as a progressive web app from Chrome, Edge or Brave and keeps working with the network switched off. It can also be cloned from GitHub and run locally with ./start.sh.

Compare two versions of a document. Entirely in your browser.