Responsibilities
| Server SDK responsibility | Description |
|---|---|
| Authenticate | Use the backend-only API Key to create and start an avatar session. |
| Connect to Motion Server | Own the WebSocket connection to Spatius. |
| Send avatar speech audio | Send the TTS output or other avatar speech audio to Motion Server. See Audio. |
| Receive encoded payloads | Receive the encoded audio payloads and motion data payloads your clients will render. |
| Hand off to transport | Deliver those encoded payloads to clients over your own WebSocket, LiveKit Room, or another transport. |
Client apps do not use your API Key. In Backend Mode Integration, your backend owns the Spatius credentials and Motion Server connection.
Next steps
Python Server SDK
Session lifecycle, audio input, callbacks, and egress options.
Go Server SDK
Go backend SDK reference and lifecycle.
Browse all demos
Every runnable demo by platform and integration path.