> ## Documentation Index > Fetch the complete documentation index at: https://docs.corbado.com/llms.txt > Use this file to discover all available pages before exploring further. # Create a login identifier for a user > Adds an `email`, `phone` or `username` login identifier to a user. A user can have multiple identifiers. Connect uses username identifiers to [map your external identity](/corbado-connect/concepts/connect-token) to the Corbado user and passkeys. This operation does not create an identity-provider session. Required API key permission: `identifiers:write`. ## OpenAPI ````yaml /api-reference/openapi/connect-backend.yaml post /users/{userID}/identifiers openapi: 3.1.1 info: version: 2.0.0 title: Corbado Backend API description: > # Introduction This documentation gives an overview of all Corbado Backend API calls to implement passwordless authentication with Passkeys. contact: name: Corbado team email: support@corbado.com url: https://www.corbado.com servers: - url: https://backendapi.cloud.corbado.io/v2 security: - basicAuth: [] - bearerAuth: [] tags: - name: ConnectTokens description: All API calls to manage connectTokens x-group: Connect tokens - name: Passkeys description: All API calls for passkey flows x-group: Passkey ceremonies - name: Users description: All API calls to manage users x-group: Users and passkeys - name: Identifiers description: All API calls to manage login identifiers x-group: Identifiers - name: PasskeyEvents description: All API calls to manage passkey events x-group: Passkey diagnostics - name: PasskeyChallenges description: All API calls to manage passkey challenges x-group: Passkey diagnostics - name: Exports description: All API calls to manage project export files x-group: Data exports - name: Connect reads description: Connect analytics, process investigation and configuration reads. x-group: Analytics and configuration - name: ConnectManagement description: Connect application and native-app configuration management. x-group: App configuration - name: ConnectRollout description: Connect rollout configuration, rulesets, targeting and simulations. x-group: Rollout configuration - name: Sessions description: All API calls to manage sessions - name: Challenges description: All API calls to manage challenges - name: SSO description: All API calls for SSO flows - name: AuthEvents description: All API calls to manage authentication events - name: ProjectConfig description: All API calls to manage project configurations - name: WebhookEndpoints description: All API calls to manage webhook endpoints - name: PasswordManagers description: All API calls to manage password managers - name: ClientEnvs description: All API calls to manage client environments - name: Devices description: All API calls to manage devices paths: /users/{userID}/identifiers: post: tags: - Identifiers summary: Create a login identifier for a user description: >- Adds an `email`, `phone` or `username` login identifier to a user. A user can have multiple identifiers. Connect uses username identifiers to [map your external identity](/corbado-connect/concepts/connect-token) to the Corbado user and passkeys. This operation does not create an identity-provider session. Required API key permission: `identifiers:write`. operationId: IdentifierCreate parameters: - $ref: '#/components/parameters/userID' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/identifierCreateReq' responses: '200': description: Identifier has been created. content: application/json: schema: $ref: '#/components/schemas/identifier' default: $ref: '#/components/responses/error' security: - basicAuth: [] - bearerAuth: - identifiers:write components: parameters: userID: name: userID in: path description: | Unique identifier of the user. Format: `usr-`. required: true schema: type: string example: usr-4693224802260150919 schemas: identifierCreateReq: type: object required: - identifierType - identifierValue - status properties: identifierType: $ref: '#/components/schemas/identifierType' identifierValue: type: string status: $ref: '#/components/schemas/identifierStatus' identifier: type: object required: - identifierID - type - value - status - userID properties: identifierID: type: string description: Unique identifier of the login identifier. example: ide-4693224802260150919 type: $ref: '#/components/schemas/identifierType' value: type: string description: Value of the identifier (here email address). example: jane@doe.com status: $ref: '#/components/schemas/identifierStatus' userID: type: string description: Unique identifier of the user. example: usr-4693224802260150919 identifierType: type: string enum: - email - phone - username identifierStatus: type: string enum: - pending - primary - verified responses: error: description: Error content: application/json: schema: allOf: - type: object required: - httpStatusCode - message - requestData - runtime properties: httpStatusCode: description: HTTP status code of operation type: integer format: int32 message: type: string example: OK requestData: description: Data about the request itself, can be used for debugging type: object required: - requestID properties: requestID: description: >- Unique ID of request, you can provide your own while making the request, if not the ID will be randomly generated on server side type: string example: req-557...663 link: description: Link to dashboard with details about request type: string example: >- https://my.corbado.com/requests/req-xxxxxxxxxxxxxxxxxxx runtime: description: Runtime in seconds for this request type: number format: float example: 0.06167686 - type: object required: - error properties: data: type: object error: type: object required: - type properties: type: description: Type of error type: string details: description: Details of error type: string validation: description: Validation errors per field type: array items: type: object required: - field - message properties: field: type: string message: type: string links: description: Additional links to help understand the error type: array items: type: string securitySchemes: basicAuth: type: http scheme: basic description: > Basic authentication is used to authenticate requests to the Backend API. The username is the project ID and the password is the API secret. The project ID and API secret can be found in the [Management Console](https://app.corbado.com/settings/api-secrets). bearerAuth: type: http scheme: bearer description: >- Use your versioned Backend API key. The key must grant the operation permission and satisfy its expiry and IP restrictions. ````