> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ninjachat.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Create Session

> Create a persistent conversation session. Use the returned session_id with the chat endpoint to maintain context across messages.



## OpenAPI

````yaml /openapi.json post /api/v1/sessions
openapi: 3.1.0
info:
  title: NinjaChat API
  version: 1.0.0
  description: >-
    Access 40+ AI models through a unified API — chat, image generation, video
    generation, and web search. One API key, one endpoint per type, just change
    the `model` parameter.
servers:
  - url: https://www.ninjachat.ai
security:
  - bearerAuth: []
paths:
  /api/v1/sessions:
    post:
      tags:
        - Sessions
      summary: Create Session
      description: >-
        Create a persistent conversation session. Use the returned session_id
        with the chat endpoint to maintain context across messages.
      operationId: createSession
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                session_id:
                  type: string
                  description: >-
                    Optional stable identifier for this session (e.g.
                    user-123-session-1). If omitted, a session_id is
                    auto-generated.
                metadata:
                  type: object
                  description: Optional metadata to associate with the session.
            examples:
              custom_id:
                summary: Custom session ID
                value:
                  session_id: user-alice-session-1
              auto_id:
                summary: Auto-generated session ID
                value: {}
      responses:
        '201':
          description: Session created.
          content:
            application/json:
              schema:
                type: object
                properties:
                  session_id:
                    type: string
                  message_count:
                    type: integer
                  created_at:
                    type: string
                    format: date-time
        '400':
          description: Invalid session payload.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Authentication failed.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
components:
  schemas:
    ErrorResponse:
      type: object
      description: >-
        OpenAI-compatible error. The top-level `message`, `code`, and
        `request_id` mirror fields inside `error` for convenience.
      properties:
        error:
          type: object
          properties:
            message:
              type: string
              description: Human-readable error description.
            type:
              type: string
              description: >-
                Error category: invalid_request_error, authentication_error,
                rate_limit_error, insufficient_quota, or api_error.
            code:
              type: string
              description: Machine-readable error code.
            param:
              type: string
              nullable: true
              description: The request parameter that caused the error, if any.
        message:
          type: string
          description: Same as error.message.
        code:
          type: string
          description: Same as error.code.
        request_id:
          type: string
          description: Unique request ID, useful when contacting support.
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: API key starting with nj_sk_

````