I was wondering why it was written in C++, but the FAQ already beat me to it.

Why build a new browser in C++ when safer and more modern languages are available?

Ladybird started as a component of the SerenityOS hobby project, which only allows C++. The choice of language was not so much a technical decision, but more one of personal convenience. Andreas was most comfortable with C++ when creating SerenityOS, and now we have almost half a million lines of modern C++ to maintain.

However, now that Ladybird has forked and become its own independent project, all constraints previously imposed by SerenityOS are no longer in effect. We are actively evaluating a number of alternatives and will be adding a mature successor language to the project in the near future. This process is already quite far along, and prototypes exist in multiple languages.

Glad to see they are open to using safer languages. C/C++ was great for its time, but we really need to move on from them.