> ## Documentation Index > Fetch the complete documentation index at: https://docs.cartesia.ai/llms.txt > Use this file to discover all available pages before exploring further. # WebRTC セッションを作成 > Creates a WebRTC session on your trusted server and returns credentials for the browser to join. Authenticate this request with an API key; access tokens, including returned session tokens, cannot create sessions. ## OpenAPI ````yaml latest.yml POST /v1/agents/webrtc/{agent_id}/sessions openapi: 3.0.1 info: title: Cartesia API version: 0.0.1 servers: - url: https://api.cartesia.ai description: Production security: [] paths: /v1/agents/webrtc/{agent_id}/sessions: post: tags: - Agents summary: Create a WebRTC session description: >- Creates a WebRTC session on your trusted server and returns credentials for the browser to join. Authenticate this request with an API key; access tokens, including returned session tokens, cannot create sessions. operationId: createAgentWebrtcSession parameters: - name: agent_id in: path description: Unique identifier for the agent. required: true schema: type: string minLength: 1 - $ref: '#/components/parameters/CartesiaVersionHeader' requestBody: required: false content: application/json: schema: $ref: '#/components/schemas/CreateAgentWebSessionRequest' responses: '200': description: The pre-created call and its browser WebRTC credentials content: application/json: schema: $ref: '#/components/schemas/CreateAgentWebrtcSessionResponse' '400': description: Invalid session configuration or missing required dynamic variables. content: application/json: schema: $ref: '#/components/schemas/PublicErrorResponse' '401': description: Missing or invalid API key. content: application/json: schema: $ref: '#/components/schemas/PublicErrorResponse' '404': description: Agent not found. content: application/json: schema: $ref: '#/components/schemas/PublicErrorResponse' '429': description: Agent concurrency limit reached. content: application/json: schema: $ref: '#/components/schemas/PublicErrorResponse' security: - APIKeyAuth: [] components: parameters: CartesiaVersionHeader: name: Cartesia-Version in: header description: API version header. required: true schema: type: string format: date example: '2026-08-14' default: '2026-08-14' enum: - '2026-08-14' schemas: CreateAgentWebSessionRequest: type: object properties: dynamic_variables: type: object additionalProperties: oneOf: - type: string - type: number - type: boolean description: >- Trusted values that Cartesia stores on the call and supplies to the agent. config_overrides: $ref: '#/components/schemas/AgentSessionConfig' CreateAgentWebrtcSessionResponse: type: object required: - call_id - url - token - room - expires_at properties: call_id: type: string description: ID of the pre-created call. url: type: string format: uri description: LiveKit server URL the browser connects to. token: type: string description: >- Short-lived LiveKit participant token for the browser connection. Do not log it. room: type: string description: LiveKit room the browser joins. expires_at: type: string format: date-time description: >- Connection deadline. Create a new session if the browser does not join before this time. PublicErrorResponse: type: object properties: doc_url: description: URL to relevant documentation for the error type: string nullable: true error_code: description: Machine-readable error code type: string nullable: true message: description: Detailed human-readable error message type: string request_id: description: >- Unique identifier for this request. Include this when contacting support. type: string title: description: Short human-readable error summary, like "File too large" type: string required: - request_id - message - title title: PublicErrorResponse AgentSessionConfig: type: object additionalProperties: false description: >- Per-call overrides using the same field structure as agent configuration. Omitted fields use the agent's published configuration. properties: instructions: type: string minLength: 1 maxLength: 200000 description: Instructions that define the agent's behavior for this call. initial_message: nullable: true type: string maxLength: 1000 description: >- Message spoken when the call begins. Set to `null` to wait for the caller to speak first. language: type: object additionalProperties: false properties: primary: allOf: - $ref: '#/components/schemas/ManagedAgentPrimaryLanguageV1' nullable: true description: >- Primary language used for this call. Omit to inherit the published language or set to `null` to use English (`en`). audio: type: object additionalProperties: false properties: output: type: object additionalProperties: false properties: voice_id: type: string minLength: 1 description: ID of the voice used for agent speech during this call. speed: nullable: true type: number minimum: 0.6 maximum: 1.5 description: >- Speech speed multiplier from `0.6` to `1.5`. Set to `null` to use the default speed. emotion: allOf: - $ref: '#/components/schemas/Emotion' nullable: true description: >- Text-to-speech emotion. Set to `null` to let the model infer the emotion from the transcript. ManagedAgentPrimaryLanguageV1: description: >- The language the agent starts each call in: a language, such as `en`, or a locale, such as `en-US`. See [supported languages and locales](/build-with-cartesia/capability-guides/advanced-capabilities#which-locales-are-supported). allOf: - $ref: '#/components/schemas/LanguageOrLocale' title: ManagedAgentPrimaryLanguageV1 Emotion: title: Emotion type: string description: >- The primary emotions are `neutral`, `calm`, `angry`, `content`, `sad`, `scared`. For more options, see [Volume, Speed, and Emotion](/build-with-cartesia/capability-guides/volume-speed-emotion#emotion-controls-beta). enum: - neutral - happy - excited - enthusiastic - elated - euphoric - triumphant - amazed - surprised - flirtatious - curious - content - peaceful - serene - calm - grateful - affectionate - trust - sympathetic - anticipation - mysterious - angry - mad - outraged - frustrated - agitated - threatened - disgusted - contempt - envious - sarcastic - ironic - sad - dejected - melancholic - disappointed - hurt - guilty - bored - tired - rejected - nostalgic - wistful - apologetic - hesitant - insecure - confused - resigned - anxious - panicked - alarmed - scared - proud - confident - distant - skeptical - contemplative - determined LanguageOrLocale: type: string enum: - en - fr - de - es - pt - zh - ja - hi - it - ko - nl - pl - ru - sv - tr - tl - bg - ro - ar - cs - el - fi - hr - ms - sk - da - ta - uk - hu - 'no' - vi - bn - th - he - ka - id - te - gu - kn - ml - mr - pa - or - ur - bg-BG - bn-IN - cs-CZ - da-DK - de-DE - el-GR - en-AU - en-CA - en-GB - en-IE - en-IN - en-NZ - en-SG - en-US - en-ZA - es-ES - es-MX - es-US - fi-FI - fr-CA - fr-FR - gu-IN - he-IL - hi-IN - hr-HR - hu-HU - id-ID - it-IT - ja-JP - ka-GE - kn-IN - ko-KR - ml-IN - mr-IN - ms-MY - nl-BE - nl-NL - no-NO - or-IN - pa-IN - pl-PL - pt-BR - pt-PT - ro-RO - ru-RU - sk-SK - sv-SE - ta-IN - te-IN - th-TH - tl-PH - tr-TR - uk-UA - ur-IN - vi-VN - zh-CN securitySchemes: APIKeyAuth: type: http scheme: bearer bearerFormat: API Key description: >- Cartesia API key (`sk_car_...`). Get one at [play.cartesia.ai/keys](https://play.cartesia.ai/keys). x-default: $CARTESIA_API_KEY ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.