This tutorial features a fully authoritative server using arcade-physics[0] for physics and collision detection. It uses Phaser for the frontend and Hathora for the backend/multiplayer.
The full code is available on Github[1]. I was pretty happy with how minimal the code ended up being, and I hope this can be a useful resource for others interested in building a multiplayer platformer game!
[0] https://github.com/yandeu/arcade-physics [1] https://github.com/hathora/platformer-tutorial