> ## Documentation Index > Fetch the complete documentation index at: https://docs.blujay.io/llms.txt > Use this file to discover all available pages before exploring further. # Add a tag to a contact > Adds a tag to the contact and returns the contact. `tag_added` tells you whether the tag was new. ## OpenAPI ````yaml /api-reference/openapi.yaml post /v1/contacts/{contact_id}/tags openapi: 3.1.0 info: title: Blujay API version: 1.0.0 description: >- The Blujay API lets you send and receive iMessage, RCS and SMS messages from your Blujay phone numbers, manage contacts, and receive real-time webhooks. Every response uses the same JSON envelope and carries a `trace_id` you can share with support. Authenticate with your workspace API key. servers: - url: https://api.blujay.io description: Production security: - PublicApiKey: [] tags: - name: Auth description: Check which workspace and credential a request is using. - name: Chats description: >- Direct and group conversations between your Blujay numbers and your contacts. - name: Messages description: Send, read, edit, unsend and retry messages. - name: Phone Numbers description: >- Your Blujay numbers, whether each can send right now, and their live sending limits. - name: Capability description: >- Check whether a phone number can be reached by iMessage, RCS or SMS before you send. - name: Contacts description: Create, find, update, tag, assign and opt out contacts. - name: vCards description: >- Saved contact cards that you can send in a message. Recipients get a native contact card over iMessage, SMS or RCS. - name: Team Members description: People in your workspace you can assign contacts to. - name: Workflows description: Enroll contacts in workflows you start manually. - name: Attachments description: >- Upload files once and reuse them in messages, or download files from messages. - name: Webhooks description: Subscribe to events, inspect delivery attempts and verify signatures. paths: /v1/contacts/{contact_id}/tags: post: tags: - Contacts summary: Add a tag to a contact description: >- Adds a tag to the contact and returns the contact. `tag_added` tells you whether the tag was new. operationId: addPublicContactTag parameters: - $ref: '#/components/parameters/ContactId' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AddPublicContactTagRequest' examples: addTag: summary: Add a tag value: tag: VIP responses: '200': description: The contact, with `tag_added`. headers: X-Trace-ID: $ref: '#/components/headers/XTraceID' content: application/json: schema: allOf: - $ref: '#/components/schemas/SuccessEnvelope' - type: object required: - data properties: data: $ref: '#/components/schemas/PublicContactTagActionResult' '400': $ref: '#/components/responses/ValidationError' '404': $ref: '#/components/responses/NotFound' security: - PublicApiKey: [] components: parameters: ContactId: name: contact_id in: path required: true schema: $ref: '#/components/schemas/ContactId' schemas: AddPublicContactTagRequest: type: object additionalProperties: false required: - tag properties: tag: type: string examples: - priority minLength: 1 maxLength: 100 SuccessEnvelope: type: object description: Wraps every successful response. The result is in `data`. required: - status - trace_id - timestamp properties: status: type: string enum: - success trace_id: $ref: '#/components/schemas/TraceId' timestamp: type: string examples: - '2026-10-14T17:01:00.000Z' format: date-time client_request_id: type: string description: >- Your `X-Request-ID` header value, echoed back when you send one. Not included on the send responses (`POST /v1/chats`, `POST /v1/chats/{chat_id}/messages`, `POST /v1/messages/{message_id}/retry`); keep your own mapping from your request ID to the returned message ID there. PublicContactTagActionResult: allOf: - $ref: '#/components/schemas/PublicContact' - type: object required: - tag_added ContactId: type: string examples: - contact_abc123 pattern: ^contact_[A-Za-z0-9_-]+$ TraceId: type: string examples: - trc_8f2a1c0e4b7d pattern: ^trc_[A-Za-z0-9_-]+$ PublicContact: type: object additionalProperties: false required: - contact_id - tags - stage - assigned_team_member - opted_out - messaging_allowed - created_at - updated_at properties: contact_id: $ref: '#/components/schemas/ContactId' phone_number: type: string examples: - '+15555550123' email: type: string examples: - ava@example.com format: email name: type: string examples: - Ava Chen tags: type: array items: type: string examples: - priority stage: type: string examples: - Active assigned_team_member: oneOf: - $ref: '#/components/schemas/PublicAssignedTeamMember' - type: 'null' opted_out: type: boolean opted_out_at: type: string examples: - '2026-10-14T17:01:00.000Z' format: date-time opted_out_source: type: string examples: - api messaging_allowed: type: boolean created_at: type: string examples: - '2026-10-14T17:01:00.000Z' format: date-time updated_at: type: string examples: - '2026-10-14T17:01:00.000Z' format: date-time created: type: boolean description: Import responses only. True when the import created a new contact. updated: type: boolean description: >- Import responses only. True when the import updated an existing contact. tag_added: type: boolean description: Add-tag responses only. True when the tag was new to this contact. stage_changed: type: boolean description: Stage responses only. True when the stage changed. assignment_changed: type: boolean description: Assignee responses only. True when the assignee changed. ErrorEnvelope: type: object description: >- Wraps every error response. Branch on `error.code`, and include `trace_id` when you contact support. required: - status - error - trace_id - timestamp properties: status: const: error error: $ref: '#/components/schemas/PublicError' trace_id: $ref: '#/components/schemas/TraceId' timestamp: type: string examples: - '2026-10-14T17:01:00.000Z' format: date-time client_request_id: type: string description: Your `X-Request-ID` header value, echoed back when you send one. PublicAssignedTeamMember: type: object additionalProperties: false required: - id - email properties: id: $ref: '#/components/schemas/MemberId' name: type: string examples: - Sam Rivera email: type: string examples: - sam@example.com format: email PublicError: type: object required: - code - message - type - http_status - retryable - doc_url - details properties: code: type: string description: Stable, machine-readable error code. Branch on this value. examples: - RATE_LIMIT_EXCEEDED - QUEUE_UNAVAILABLE - FEATURE_NOT_ENABLED message: type: string description: Human-readable explanation. It can change, so don't parse it. type: type: string description: Broad error category. examples: - validation - auth - idempotency - rate_limit - queue - feature_gate http_status: type: integer description: The HTTP status code of the response. enum: - 400 - 401 - 403 - 404 - 409 - 413 - 415 - 422 - 429 - 500 - 502 - 503 retryable: type: boolean description: Whether sending the same request again later can succeed. doc_url: type: string format: uri description: Link to documentation for this error code. details: type: array description: >- Extra structured context, such as the fields that failed validation or the limit you hit. items: type: object additionalProperties: true retry_after: type: integer minimum: 1 description: >- Seconds to wait before retrying. Also sent as the `Retry-After` header. reset_at: type: string examples: - '2026-10-14T17:01:00.000Z' format: date-time description: When the limit you hit resets. MemberId: type: string examples: - member_abc123 pattern: ^member_[A-Za-z0-9_-]+$ headers: XTraceID: description: >- Unique ID for this request. It matches `trace_id` in the body. Include it when you contact Blujay support. schema: $ref: '#/components/schemas/TraceId' responses: ValidationError: description: The request is invalid. `details` lists the fields that failed. headers: X-Trace-ID: $ref: '#/components/headers/XTraceID' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' examples: invalidInput: value: status: error error: code: VALIDATION_ERROR message: Request validation failed type: validation http_status: 400 retryable: false doc_url: https://docs.blujay.io/errors/validation-error details: [] trace_id: trc_8f2a1c0e4b7d timestamp: '2026-10-14T00:00:00.000Z' NotFound: description: The resource doesn't exist or isn't in your workspace. headers: X-Trace-ID: $ref: '#/components/headers/XTraceID' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' securitySchemes: PublicApiKey: type: http scheme: bearer bearerFormat: blu_... description: > Your workspace API key, sent as `Authorization: Bearer blu_...`. Workspace admins can find it in the Blujay app under **API**. An API key has full access to your workspace and works on every endpoint. There is no test mode: every key sends real messages and changes real data, so keep it secret and use it only from your server. Each API key can make 600 read requests and 120 write requests per minute, plus 60 attachment requests per minute. Over a limit you get `429 RATE_LIMIT_EXCEEDED` with `Retry-After`. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.