[sph]

To be fair Qt is just to create the window on Linux, but all the browser internals are their own.

[greenthrow]

It's also being used for networking.

[LeFantome]

For now…

Everything is from scratch on SerenityOS. Ladybird takes as much of that as it can but the is not afraid to use existing tech for the bits of Serenity that cannot currently be used on Linux ( the GUi framework and networking ).