Is Spotify built on Python?

Yes, but it is built around a C++ core , which is also shared by the iOS and Android clients. You can say that it is built with JavaScript to the same extent that the iOS client is made in Objective-C and the Android client is made in Java.28 Eyl 2011

Spotify’s backend consists of many interdependent services, connected by own messaging protocol over ZeroMQ. Around 80% of these services are written in Python . The non-Python services are typically written in Java, although we do have a few using C or C++. Speed is a big focus for Spotify.20 Mar 2013

Is the mobile app of Spotify also based on electron? No, electron is only for Desktop.