Animation studio

I'm not really clear which studio(s) animated both Superman TAS and The New Batman Adventures. I get that it's a Warner Bros production, but who animated it and where (what country)? Previously Batman TAS was animated by various overseas animation studios, so I wasn't sure. I'm just wondering because the animation quality was pretty damn good.

While I liked a lot of BTAS's various art styles by its various animation studios they used, it got annoying to see the artwork always change from episode to episode (Ninja Turtles [1987] and Fox's Peter Pan and the Pirates were other examples of this). But with STAS and TNBA, at least the animation is decent and consistent.