Colyseus and Nakama are both really good options! There’s also:
- NoobHub: GitHub - britzl/NoobHub: Network multiplayer and messaging for CoronaSDK, Moai, Gideros & LÖVE - Only the multiplayer part, no matchmaking
- Building a Multiplayer Server
Edit: The Nakama service recently did a big update of their API and the Defold Tic-Tac-Toe example has not been updated to the new version. I’ll try to do this soon. The basic principles still apply though.