A useless add-on for a useless site.
The underlying idea is good, but the implementation is terrible.

Everything is tied to their website, which is rarely accessible or stable.
And even if everything is fine with the site, the software itself is full of bugs.
Let’s add to this the “security” policy (due to which, in the event of critical failures, it is faster to create a new account than to wait 5 days or longer if you need an answer on Github) and the result is a completely unacceptable product.

https://github.com/keybase/keybase-issues/issues/4178#issue-1628402225

On top of existing issues (all of which XY hit on the head 3 months ago, https://addons.mozilla.org/en-US/firefox/addon/keybase-for-firefox/reviews/1505639/?src=search) they have now sold out to Zoom, who is in the process of putting encryption and privacy for its users behind a paywall.

they are fanboys of themselves and do not address serious concerns and misgivings of the community of privacy-conscious users. Their verbiage cannot be taken seriously. Their tooling is unfathomable. No src-package in Arch/AUR? WTF?
1. "Keybase uses root privileges only for making the magic /keybase directory available." WTF?
2. "you shouldn’t just run this code without reading it, as it may have bugs or stubbed out crypto"
3. "it might not do exactly what it says it is doing " WTF ??

Three huge RED ALERT flags right there for you. You have been warned! Be either safe or sorry!

The Keybase isn't communicating with add-on under Linux, the add-on for Chromium works fine.

Doesn't work at all. The icon on the toolbar doesn't do anything when clicked, and this error appears in the browser console: "TypeError: this.browser is null ExtensionPopups.jsm:319:7"

I'm running on Nightly 59. I believe this is caused by this webextensions bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1394019