They were doing their own custom language before Swift.

didn't know

> The browser and libraries are all written in C++. (While our own memory-safe Jakt language is in heavy development, it’s not yet ready for use in Ladybird.)

https://awesomekling.github.io/Ladybird-a-new-cross-platform...

only thing I could find - has it been actually used in Ladybird after all?

	▲	LeFantome 5 hours ago \| parent [-]
		No, they never completed or adopted their own language. It was back in the SerenityOS days, before the browser forked into its own project. https://github.com/SerenityOS/jakt