Comment by latexr
> They claim so much and their browsers' code is 100% proprietary
Far from me to defend Arc (I dislike it for several reasons) but it’s based on Chromium so it’s far from 100% proprietary. Don’t Edge, Vivaldi, and even Chrome have proprietary layers on top of the open-source Chromium?
Vivaldi's inhouse UI code isn't open source, but is visible for users to verify AFAIK.