I heard around the internet that Firefox on Android does not have Site Isolation built-in yet. After a little bit of research, I learned that Site Isolation on Android was added in Firefox Nightly, appearing to have been added sometime in June 2023. What I can’t find, though, is whether this has ever been added to any stable versions of Firefox yet. Does anyone know anything about this?

Update: After further research, it appears that Site Isolation is not currently a feature in stable version of Firefox on Android. I don’t know with certainty if their information is up-to-date, but GrapheneOS (A well-known privacy/security-focused fork of Android) does not recommend using Firefox-based browsers on Android due to it’s (apparently) lack of a Site Isolation feature. A snippet of what Graphene currently have to say about Firefox on Android/GrapheneOS from their usage guide page, is: “Avoid Gecko-based browsers like Firefox as they’re currently much more vulnerable to exploitation and inherently add a huge amount of attack surface.”

On a side-note, they also say about Firefox’s current Site Isolation on desktop being weaker, which I wasn’t aware of. “Even in the desktop version, Firefox’s sandbox is still substantially weaker (especially on Linux) and lacks full support for isolating sites from each other rather than only containing content as a whole.”