Chat | Hume API

Chat with Empathic Voice Interface (EVI)

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WSS

wss://api.hume.ai/v0/evi/chat

Query Parameters

access_tokenstringOptionalDefaults to

Access token used for authenticating the client. If not provided, an api_key must be provided to authenticate.

The access token is generated using both an API key and a Secret key, which provides an additional layer of security compared to using just an API key.

For more details, refer to the Authentication Strategies Guide.

Access token used for authenticating the client. If not provided, an `api_key` must be provided to authenticate. The access token is generated using both an API key and a Secret key, which provides an additional layer of security compared to using just an API key. For more details, refer to the [Authentication Strategies Guide](/docs/introduction/api-key#authentication-strategies).

allow_connectionbooleanOptionalDefaults to false

Allows external connections to this chat via the /connect endpoint.

config_idstringOptional

The unique identifier for an EVI configuration.

Include this ID in your connection request to equip EVI with the Prompt, Language Model, Voice, and Tools associated with the specified configuration. If omitted, EVI will apply default configuration settings.

For help obtaining this ID, see our Configuration Guide.

The unique identifier for an EVI configuration. Include this ID in your connection request to equip EVI with the Prompt, Language Model, Voice, and Tools associated with the specified configuration. If omitted, EVI will apply [default configuration settings](/docs/speech-to-speech-evi/configuration/build-a-configuration#default-configuration). For help obtaining this ID, see our [Configuration Guide](/docs/speech-to-speech-evi/configuration).

config_versionintegerOptional

The version number of the EVI configuration specified by the config_id.

Configs, as well as Prompts and Tools, are versioned. This versioning system supports iterative development, allowing you to progressively refine configurations and revert to previous versions if needed.

Include this parameter to apply a specific version of an EVI configuration. If omitted, the latest version will be applied.

The version number of the EVI configuration specified by the `config_id`. Configs, as well as Prompts and Tools, are versioned. This versioning system supports iterative development, allowing you to progressively refine configurations and revert to previous versions if needed. Include this parameter to apply a specific version of an EVI configuration. If omitted, the latest version will be applied.

event_limitintegerOptional

The maximum number of chat events to return from chat history. By default, the system returns up to 300 events (100 events per page × 3 pages). Set this parameter to a smaller value to limit the number of events returned.

resumed_chat_group_idstringOptional

The unique identifier for a Chat Group. Use this field to preserve context from a previous Chat session.

A Chat represents a single session from opening to closing a WebSocket connection. In contrast, a Chat Group is a series of resumed Chats that collectively represent a single conversation spanning multiple sessions. Each Chat includes a Chat Group ID, which is used to preserve the context of previous Chat sessions when starting a new one.

Including the Chat Group ID in the resumed_chat_group_id query parameter is useful for seamlessly resuming a Chat after unexpected network disconnections and for picking up conversations exactly where you left off at a later time. This ensures preserved context across multiple sessions.

There are three ways to obtain the Chat Group ID:

Chat Metadata: Upon establishing a WebSocket connection with EVI, the user receives a Chat Metadata message. This message contains a chat_group_id, which can be used to resume conversations within this chat group in future sessions.
List Chats endpoint: Use the GET /v0/evi/chats endpoint to obtain the Chat Group ID of individual Chat sessions. This endpoint lists all available Chat sessions and their associated Chat Group ID.
List Chat Groups endpoint: Use the GET /v0/evi/chat_groups endpoint to obtain the Chat Group IDs of all Chat Groups associated with an API key. This endpoint returns a list of all available chat groups.

The unique identifier for a Chat Group. Use this field to preserve context from a previous Chat session. A Chat represents a single session from opening to closing a WebSocket connection. In contrast, a Chat Group is a series of resumed Chats that collectively represent a single conversation spanning multiple sessions. Each Chat includes a Chat Group ID, which is used to preserve the context of previous Chat sessions when starting a new one. Including the Chat Group ID in the `resumed_chat_group_id` query parameter is useful for seamlessly resuming a Chat after unexpected network disconnections and for picking up conversations exactly where you left off at a later time. This ensures preserved context across multiple sessions. There are three ways to obtain the Chat Group ID: - [Chat Metadata](/reference/speech-to-speech-evi/chat#receive.ChatMetadata): Upon establishing a WebSocket connection with EVI, the user receives a Chat Metadata message. This message contains a `chat_group_id`, which can be used to resume conversations within this chat group in future sessions. - [List Chats endpoint](/reference/speech-to-speech-evi/chats/list-chats): Use the GET `/v0/evi/chats` endpoint to obtain the Chat Group ID of individual Chat sessions. This endpoint lists all available Chat sessions and their associated Chat Group ID. - [List Chat Groups endpoint](/reference/speech-to-speech-evi/chat-groups/list-chat-groups): Use the GET `/v0/evi/chat_groups` endpoint to obtain the Chat Group IDs of all Chat Groups associated with an API key. This endpoint returns a list of all available chat groups.

verbose_transcriptionbooleanOptionalDefaults to false

A flag to enable verbose transcription. Set this query parameter to true to have unfinalized user transcripts be sent to the client as interim UserMessage messages. The interim field on a UserMessage denotes whether the message is “interim” or “final.”

A flag to enable verbose transcription. Set this query parameter to `true` to have unfinalized user transcripts be sent to the client as interim UserMessage messages. The [interim](/reference/speech-to-speech-evi/chat#receive.UserMessage.interim) field on a [UserMessage](/reference/speech-to-speech-evi/chat#receive.UserMessage) denotes whether the message is "interim" or "final."

api_keystringOptionalDefaults to

API key used for authenticating the client. If not provided, an access_token must be provided to authenticate.

For more details, refer to the Authentication Strategies Guide.

session_settingsobjectOptional

Send

AudioInputobjectRequired

When provided, the input is audio.

SessionSettingsobjectRequired

Settings for this chat session.

UserInputobjectRequired

User text to insert into the conversation. Text sent through a User Input message is treated as the user's speech to EVI. EVI processes this input and provides a corresponding response. Expression measurement results are not available for User Input messages, as the prosody model relies on audio input and cannot process text alone.

AssistantInputobjectRequired

When provided, the input is spoken by EVI.

ToolResponseMessageobjectRequired

When provided, the output is a function call response.

ToolErrorMessageobjectRequired

When provided, the output is a function call error.

PauseAssistantMessageobjectRequired

Pause responses from EVI. Chat history is still saved and sent after resuming.

ResumeAssistantMessageobjectRequired

Resume responses from EVI. Chat history sent while paused will now be sent.

Receive

SubscribeEventobjectRequired

URL	wss://api.hume.ai/v0/evi/chat
Method	GET
Status	101 Switching Protocols