> ## Documentation Index
> Fetch the complete documentation index at: https://docs.16tms.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Register for Tournament

> Register a user for a tournament using their external ID. Note: Before joining, the user must have linked their user game ID. This endpoint is for solo participant tournaments only.



## OpenAPI

````yaml /api-reference/tournament-registrations/openapi.json post /tournaments/{tournamentId}/registrations/by-external-id
openapi: 3.0.0
info:
  title: Tournament Registrations
  version: 1.0.0
  description: API endpoints for tournament registrations
servers:
  - url: https://api.16tms.com/api/v1
    description: Production server
security:
  - ApiKeyAuth: []
paths:
  /tournaments/{tournamentId}/registrations/by-external-id:
    post:
      summary: Register for Tournament
      description: >-
        Register a user for a tournament using their external ID. Note: Before
        joining, the user must have linked their user game ID. This endpoint is
        for solo participant tournaments only.
      operationId: registerTournamentByExternalId
      parameters:
        - name: tournamentId
          in: path
          required: true
          schema:
            type: string
          description: The unique identifier of the tournament
        - name: participantExternalId
          in: query
          required: true
          schema:
            type: string
          description: The external ID of the participant
      requestBody:
        required: false
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/RegisterTournamentRequest'
      responses:
        '200':
          description: Registration successful
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/RegisterTournamentResponse'
        '409':
          description: Conflict - User already registered or game account not linked
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
components:
  schemas:
    RegisterTournamentRequest:
      type: object
      properties:
        applicationMessage:
          type: string
          nullable: true
          description: Optional message from the applicant.
        password:
          type: string
          nullable: true
          description: Password for password-protected tournaments.
        payment:
          type: object
          properties:
            transactionId:
              type: string
            amount:
              type: number
            currencyId:
              type: string
              format: uuid
            paymentMethod:
              type: string
          description: Payment details for paid tournaments.
    RegisterTournamentResponse:
      type: object
      properties:
        success:
          type: boolean
          example: true
        message:
          type: string
          example: Registration successful
        data:
          $ref: '#/components/schemas/RegistrationData'
        meta:
          $ref: '#/components/schemas/Meta'
    ErrorResponse:
      type: object
      properties:
        success:
          type: boolean
          example: false
        error:
          type: object
          properties:
            code:
              type: string
              example: BUSINESS_RULE_VIOLATION
            message:
              type: string
              example: Participant is not eligible
        meta:
          $ref: '#/components/schemas/Meta'
    RegistrationData:
      type: object
      properties:
        registrationId:
          type: string
          example: d8c3e4de-117a-4f69-994c-68698db6f938
        tournamentId:
          type: string
          example: 0fe60e24-f120-45a4-baab-6bdab592b6b7
        tournamentName:
          type: string
          example: Auto Test Tournament
        participantId:
          type: string
          example: 0cc2b3d5-71ad-49dc-ab7d-f35ba6bc0d55
        participantType:
          type: integer
          example: 2
        participantName:
          type: string
          nullable: true
          example: string
        status:
          type: integer
          example: 2
        entryFeePaid:
          type: number
          example: 50
        paymentStatus:
          type: string
          example: PendingPayment
    Meta:
      type: object
      properties:
        traceId:
          type: string
          example: 00-f125448ab05644fa80f36b22f1d71ac5-0124b07dc253ea94-00
        elapsedMs:
          type: number
          example: 70.26
        serverTimestamp:
          type: string
          format: date-time
          example: '2026-02-12T11:21:26.4669586Z'
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: X-API-KEY
      description: API key for authentication.

````