Rust is definitely used in Firefox, but Servo[0], which was going to be the replacement browser engine (or at least the testbed for that), was abandoned by Mozi

Rust is definitely used in Firefox, but Servo[0], which was going to be the replacement browser engine (or at least the testbed for that), was abandoned by Mozilla, in a limbo for some time and now under new stewardship. On a meta-level, I think the story that people like to tell is that Mozilla chose increasing executive compensation rather than using the same money to keep the Servo (and people working on Rust itself) employed. [0]: https://servo.org https://servo.org