> ## Documentation Index > Fetch the complete documentation index at: https://docs.zuddl.com/llms.txt > Use this file to discover all available pages before exploring further. # Record a session check-in > Marks the attendee identified by the supplied QR code as checked into the given session. Intended for onsite check-in partners (e.g. RFID badge-scan vendors). The QR code may be supplied either as the raw code or as a Zuddl deep-link URL (e.g. https://applink.zuddl.com/link/com.zuddl.portal/{eventId}/profile/{qrCode}); the server extracts the trailing path segment when a URL is supplied. Session attendance is recorded against the user's Zuddl account; if the scanned registration is not yet linked to an account, the request is rejected with 422. Required API key scopes: `WRITE` **This API can only be called with an access key that was generated for Backend usage.** ## OpenAPI ````yaml https://api.prod.zuddl.com/api/v3/api-docs/api-product post /v1/events/{eventId}/sessions/{sessionId}/attendance/checkin openapi: 3.1.0 info: title: Zuddl API Documentation description: >- Zuddl RESTful APIs let you interact with the Zuddl platform and take action for your event or webinar. They let you add attendees, get attendee details, get event details, and more. The API response is returned in JSON, which your systems can easily consume. The API parameters allow you to customize the response using filters, sorting, pagination, and other parameters. Parameter values should be percent-encoded (URL-encoded) to ensure correct transmission, especially if they contain special characters such as spaces, semi-colons, or slashes. # Rate limits | Metrics | Value | | --- | --- | | Requests/second | 10 | | Burst or no. of concurrent calls allowed | 100 requests | | Total quota | 10000 requests/day | version: '1.0' servers: - url: https://api.zuddl.com/ security: - api_key: [] tags: - name: Events description: API endpoints for managing events - name: Attendees description: >- The attendee APIs let you add and retrieve attendee in a particular event type. - name: Sessions description: API endpoints for managing event sessions - name: Speakers description: API endpoints for managing event speakers - name: Sponsors description: API endpoints for managing event sponsors - name: Locations description: API endpoints for managing event locations paths: /v1/events/{eventId}/sessions/{sessionId}/attendance/checkin: post: tags: - Sessions summary: Record a session check-in description: >- Marks the attendee identified by the supplied QR code as checked into the given session. Intended for onsite check-in partners (e.g. RFID badge-scan vendors). The QR code may be supplied either as the raw code or as a Zuddl deep-link URL (e.g. https://applink.zuddl.com/link/com.zuddl.portal/{eventId}/profile/{qrCode}); the server extracts the trailing path segment when a URL is supplied. Session attendance is recorded against the user's Zuddl account; if the scanned registration is not yet linked to an account, the request is rejected with 422. Required API key scopes: `WRITE` **This API can only be called with an access key that was generated for Backend usage.** operationId: checkInToSession parameters: - name: eventId in: path description: Unique identifier of the event required: true schema: type: string pattern: >- ^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$ example: 4fcebf73-3ddb-4fe6-b56d-5dd7dedb7c3d - name: sessionId in: path description: Unique identifier of the session required: true schema: type: string example: 4fcebf73-3ddb-4fe6-b56d-5dd7dedb7c3g requestBody: content: application/json: schema: $ref: >- #/components/schemas/org.events.app.domain.api_product.event.attendance.dtos.AttendanceCheckInRequest required: true responses: '200': description: Session check-in recorded content: application/json: schema: $ref: >- #/components/schemas/org.events.app.domain.api_product.event.attendance.dtos.AttendanceCheckInResponse '400': description: Invalid input content: application/json: schema: $ref: >- #/components/schemas/org.events.app._internal._response.v1.ApiErrorResponse '401': description: Unauthorized content: application/json: schema: $ref: >- #/components/schemas/org.events.app._internal._response.v1.ApiErrorResponse '404': description: >- Session not found in this event, or QR code did not match a registration content: application/json: schema: $ref: >- #/components/schemas/org.events.app._internal._response.v1.ApiErrorResponse '409': description: Session check-in is disabled for this session (CHECK_IN_DISABLED) content: application/json: schema: $ref: >- #/components/schemas/org.events.app._internal._response.v1.ApiErrorResponse '422': description: >- Either ACCOUNT_NOT_LINKED (scanned registration is not yet linked to a Zuddl account) or INELIGIBLE_FOR_SESSION (attendee is not in the session's configured audience for its check-in permission type) content: application/json: schema: $ref: >- #/components/schemas/org.events.app._internal._response.v1.ApiErrorResponse components: schemas: org.events.app.domain.api_product.event.attendance.dtos.AttendanceCheckInRequest: properties: qrCode: type: string description: >- QR code identifying the attendee. Accepts either the raw code (e.g. "EAFPSNAB2I") or a Zuddl deep-link URL such as "https://applink.zuddl.com/link/com.zuddl.portal/{eventId}/profile/{qrCode}" — the server extracts the trailing path segment when a URL is supplied. example: EAFPSNAB2I minLength: 1 occurredAt: type: string format: date-time description: >- ISO-8601 timestamp of the scan from the partner's device. Defaults to the server time when omitted. example: '2026-06-12T14:33:00Z' required: - qrCode org.events.app.domain.api_product.event.attendance.dtos.AttendanceCheckInResponse: properties: registrationId: type: string format: uuid description: >- Resolved registration id for the attendee. Null when the scanned user is a speaker without a registration record. example: 4fcebf73-3ddb-4fe6-b56d-5dd7dedb7c3d accountId: type: string format: uuid description: Resolved Zuddl account id for the user. example: 9e2b6d4a-6c3a-4a7e-8d24-1c2f8a31a812 speakerId: type: string format: uuid description: >- Speaker id when the scanned user is a speaker for this event. Null otherwise. example: d812a64f-8865-4289-9024-9a120792c3d8 role: type: string description: Resolved role of the scanned user within the event. enum: - ATTENDEE - ORGANIZER - SPEAKER - SPONSOR - MODERATOR example: ATTENDEE action: type: string description: Action recorded for this scan. enum: - CHECK_IN - CHECK_OUT example: CHECK_IN recordedAt: type: string format: date-time description: >- Timestamp recorded for the scan (echoes the request occurredAt or the server time used when omitted). example: '2026-06-12T14:33:00Z' org.events.app._internal._response.v1.ApiErrorResponse: properties: timestamp: type: string format: date-time message: type: string description: type: string errors: type: object additionalProperties: type: string securitySchemes: api_key: type: apiKey description: Provide your API key secret in the `Authorization` header name: Authorization in: header ````