Regularly breaks. What I mean is that, if you log in and enable the VPN upon first installing it works. Then use firefox as normal, exit firefox, open firefox again etc. and eventually the addon will just hang. You click the little icon to manage it and it just shows a loading wheel. Won't let firefox connect to the internet while it sits there broken. The only fix is to uninstall and reinstall the addon which requires logging in all over again. Very buggy.
Additionally, leaks DNS.

You should let me use the free version first so that I can see if the product is good or not before buying it, but no, you keep popping up notifications to buy, buy, buy, and choose not to let me use the free version. Well, you chose to be the world's worst VPN extension.

Missing refresh token

Love Proton VPN!! Easy to use and inexpensive.

Simple d'utilisation et bien intégré au navigateur

[WasteOfTime] Proton sounds so legit n rightous, - but if you look close things change fast... whats the use of an VPN if you cant install it!? 8/10 of the installation guides does not work and create a rabbit-hole in the FAQ section, that draws more question than it solves... IT IS INSANE what happens here barely possible to install and use at all.... BUT HEY : YOU JUST HAVE TO UPGRADE TO PbLAN RIGHT - THEN ALL WILL BE GONE ....ah.. 4sure NOT ....LOL Seriously dont waste your time here its insane: "If you make an extension and deny the people the fact that it s not possible in the free edition YOU LIE 2 THEM !!! ...and waste their time through your censouring - framing into an ALL IS GOOD onesidet point of view. How zynical asking for support against censorship! But dont have the guts to indicate negative aspects from the beginning to stay concise!???

Leaking DNS requests. Doesnt save login data well

Completely unusable for free users. At the very least, I should be allowed to use it to configure options available to a free account and not just be stuck with the regular app to do the same thing.

Free version is non-functional, don't waste your time setting up an account.

very good

Works fine, don't have any complains as others do here (no DNS leak, no connection issues and also works with Firefox Containers for me)

VPN doesn't work with Firefox Containers. Split tunnel is only whitelist mode when it should be blacklist instead. Doesn't have the same feature set as the desktop app. Plus Proton is stubborn in not implementing SOCKS5 to make it work with Firefox Containers even though Mullvad does it.

For anyone coming here, just subscribe to Mullvad instead and use the advanced proxy settings for Firefox containers.