This page documents the public API for the Speech Engine Python SDK (`elevenlabs`). ## Getting a Speech Engine resource Retrieve a `SpeechEngineResource` by its engine ID. The returned object provides methods to start a server, verify requests, or create individual sessions. ```python from elevenlabs import AsyncElevenLabs elevenlabs = AsyncElevenLabs() engine = await elevenlabs.speech_engine.get("seng_8k3m9xr4hjnfg983brhmhkd98n6") ``` ## SpeechEngineResource ### Properties | Property | Type | Description | | ----------- | ----- | ---------------------------- | | `engine_id` | `str` | The ID of the speech engine. | ### serve Start a standalone WebSocket server. Blocks until stopped. ```python await engine.serve( port=3001, path="/ws", debug=True, on_transcript=handle_transcript, ) ``` | Parameter | Type | Default | Description | | --------------- | ---------- | ------- | --------------------------------------------------------------------------------------------------------- | | `port` | `int` | `3001` | Port to listen on. | | `path` | `str` | `None` | Restrict connections to this path. `None` accepts all. | | `debug` | `bool` | `False` | Enable debug logging to stdout. | | `disable_auth` | `bool` | `False` | Skip JWT verification on incoming connections. See [Disabling authentication](#disabling-authentication). | | `on_init` | `callable` | | Called when a session is initialized. | | `on_transcript` | `callable` | | Called when a user transcript arrives. | | `on_close` | `callable` | | Called on clean disconnect. | | `on_disconnect` | `callable` | | Called when the WebSocket drops unexpectedly. | | `on_error` | `callable` | | Called on protocol or WebSocket errors. | #### Disabling authentication By default `serve()` verifies the `X-Elevenlabs-Speech-Engine-Authorization` header on every incoming connection. If your server sits behind an infrastructure layer that already restricts incoming traffic to ElevenLabs (typically an IP allowlist scoped to [ElevenLabs' egress ranges](/guides/elevenapi-resources-ip-allowlisting)), you can skip JWT verification by passing `disable_auth=True`: ```python # No api_key required when disable_auth is True await engine.serve(port=3001, disable_auth=True, on_transcript=on_transcript) # Or directly on SpeechEngineServer from elevenlabs.speech_engine import SpeechEngineServer server = SpeechEngineServer(port=3001, disable_auth=True, on_transcript=on_transcript) await server.serve() ``` When auth is disabled the server accepts any client that can reach it and emits a `UserWarning` on startup. :::callout{intent="warning"} Only use `disable_auth=True` if you have an IP allowlist, custom header values or equivalent network-level restriction in front of the server. Without one, anyone on the internet can open a session and consume your compute and downstream LLM quota. ::: ### verify\_request Verify that an incoming request originates from the ElevenLabs Speech Engine API. Checks the `X-Elevenlabs-Speech-Engine-Authorization` header for a valid JWT signed with the SHA-256 hash of your API key. Only needed when managing the WebSocket upgrade yourself. When using `serve()`, verification is handled automatically (unless `disable_auth=True` was set). ```python is_valid = engine.verify_request(headers) ``` | Parameter | Type | Description | | --------- | ------ | --------------------------- | | `headers` | `dict` | Request headers dictionary. | **Returns:** `bool` — `True` if the request is valid. ### create\_session Wrap an accepted WebSocket in a `SpeechEngineSession`. Use this for custom server integration (e.g. FastAPI, Starlette, or manual WebSocket handling). ```python session = engine.create_session(websocket, debug=True) session.on("user_transcript", handle_transcript) await session.run() ``` | Parameter | Type | Default | Description | | --------- | --------- | ------- | --------------------------------- | | `ws` | WebSocket | | An accepted WebSocket connection. | | `debug` | `bool` | `False` | Enable debug logging. | **Returns:** `SpeechEngineSession` ## SpeechEngineSession Wraps a single WebSocket connection. Each connection represents one conversation. The session emits events for transcripts and lifecycle changes, and provides methods to send LLM responses back. When a new transcript arrives, the previous transcript handler is cancelled automatically, interrupting any in-flight LLM call. ### Properties | Property | Type | Description | | ----------------- | --------------- | ---------------------------------------------------------------- | | `conversation_id` | `Optional[str]` | The conversation ID assigned by the API. Available after `init`. | | `is_open` | `bool` | Whether the session is still open. | ### on Register a handler for an event. Returns the session for chaining. ```python session.on("user_transcript", handler) ``` ### off Remove a previously registered handler. ```python session.off("user_transcript", handler) ``` ### once Register a handler that fires once then removes itself. ```python session.once("init", handler) ``` ### send\_response Send an LLM response back to the Speech Engine API for text-to-speech synthesis. Must be called inside an `on_transcript` handler. Calling it outside of a handler emits a warning and returns without sending. ```python # String response await session.send_response("Hello, how can I help?") # Streamed response (OpenAI, Anthropic, or Gemini) stream = await openai_client.responses.create(model="gpt-4o", input=messages, stream=True) await session.send_response(stream) ``` | Parameter | Type | Description | | ---------- | ----------------------- | -------------------------------------------------------------------------- | | `response` | `str` \| async iterable | A complete string or an async iterable of text chunks / LLM stream events. | The SDK auto-detects and extracts text from the following LLM stream formats: | Provider | Event format | | ----------------------- | ------------------------------------------------------------------------------ | | OpenAI Responses API | `{ type: "response.output_text.delta", delta: "text" }` | | OpenAI Chat Completions | `{ choices: [{ delta: { content: "text" } }] }` | | Anthropic Messages API | `{ type: "content_block_delta", delta: { type: "text_delta", text: "text" } }` | | Google Gemini API | `{ candidates: [{ content: { parts: [{ text: "text" }] } }] }` | ### run Run the receive loop until the WebSocket closes. This is the main entry point after constructing a session manually via `create_session()`. ```python session = engine.create_session(websocket) session.on("user_transcript", handle_transcript) await session.run() ``` ### close Close the session and the underlying WebSocket connection. ```python session.close() ``` ## Callbacks The keyword arguments passed to `serve()`. All callbacks are optional. Handlers can be synchronous or asynchronous (coroutine) functions. | Callback | Signature | Description | | --------------- | ----------------------------------------- | ------------------------------------------- | | `on_init` | `(conversation_id: str, session) -> None` | Session initialized with a conversation ID. | | `on_transcript` | `(transcript: list, session) -> None` | User speech transcribed. | | `on_close` | `(session) -> None` | Clean disconnect from ElevenLabs. | | `on_disconnect` | `(session) -> None` | WebSocket dropped unexpectedly. | | `on_error` | `(error: Exception, session) -> None` | Protocol or WebSocket error. | ## Events When using `session.on()` directly instead of callbacks, these are the event names and their handler signatures. | Event | Handler signature | | ----------------- | ----------------------------------------- | | `user_transcript` | `(transcript: list[ConversationMessage])` | | `init` | `(conversation_id: str)` | | `close` | `()` | | `disconnected` | `()` | | `error` | `(error: Exception)` | Event name constants are available for type-safe usage: ```python from elevenlabs.speech_engine import USER_TRANSCRIPT, INIT, CLOSE, DISCONNECTED, ERROR session.on(USER_TRANSCRIPT, handle_transcript) ``` ## ConversationMessage A single message in the conversation history. The full transcript is passed to `on_transcript` on every turn. | Property | Type | Description | | --------- | --------------------- | -------------------------------- | | `role` | `"user"` \| `"agent"` | Who sent the message. | | `content` | `str` | The text content of the message. | ## Wire protocol For reference, these are the JSON messages exchanged over the WebSocket connection. The SDK handles serialization and deserialization automatically. ### Incoming (ElevenLabs API to developer server) | Message type | Fields | Description | | ----------------- | ---------------------------------------------------------- | ----------------------------------- | | `init` | `conversation_id: string` | Session initialized. | | `user_transcript` | `user_transcript: TranscriptMessage[]`, `event_id: number` | User speech transcribed. | | `ping` | | Keep-alive. SDK responds with pong. | | `close` | | Clean disconnect. | | `error` | `message: string` | Error from the API. | ### Outgoing (developer server to ElevenLabs API) | Message type | Fields | Description | | ---------------- | ---------------------------------------------------------- | ------------------------------------- | | `agent_response` | `content: string`, `event_id: number`, `is_final: boolean` | LLM response chunk for TTS synthesis. | | `pong` | | Response to ping. | ## Related pages - [Administration](./administration-index.md) - [API reference](./api-reference-index.md) - [Changelog](./changelog-index.md) - [ElevenAgents](./elevenagents-index.md) - [ElevenAPI](./elevenapi-index.md) - [ElevenCreative](./elevencreative-index.md) - [ElevenLabs Documentation Docs](../index.md) - [General Troubleshooting FAQ](./troubleshooting-index.md) - [General Website FAQ](./website-index.md) - [Help Center](./help-center-2-index.md) # Agent Instructions Cite this page’s canonical URL and keep its documentation version. 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