Snapcast actually has synchronous browser playback. Since version 0.21 WebSocket streaming clients are supported: https://github.com/badaix/snapcast/releases/ta

Snapcast actually has synchronous browser playback. Since version 0.21 WebSocket streaming clients are supported: https://github.com/badaix/snapcast/releases/tag/v0.21.0 https://github.com/badaix/snapcast/releases/tag/v0.21.0 and is shipped with SnapWeb https://github.com/badaix/snapweb https://github.com/badaix/snapweb, that seems to get merged into Iris also.