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

# Update a contact

> Update a contact's fields. Only the provided fields will be updated. You can also sync lists and properties inline.



## OpenAPI

````yaml PUT /contacts/{id}
openapi: 3.1.0
info:
  title: SendKit API
  description: The SendKit API allows you to send transactional emails programmatically.
  version: 1.0.0
servers:
  - url: https://api.sendkit.dev
security:
  - bearerAuth: []
paths:
  /contacts/{id}:
    put:
      tags:
        - Contacts
      summary: Update a contact
      description: >-
        Update a contact's fields. Only the provided fields will be updated. You
        can also sync lists and properties inline.
      operationId: updateContact
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: string
            format: uuid
          description: The contact ID.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/UpdateContactRequest'
      responses:
        '200':
          description: Contact updated successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Contact'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/ValidationError'
components:
  schemas:
    UpdateContactRequest:
      type: object
      properties:
        email:
          type: string
          format: email
          maxLength: 255
          description: The contact's email address.
          example: john@example.com
        first_name:
          type:
            - string
            - 'null'
          maxLength: 255
          description: The contact's first name.
          example: John
        last_name:
          type:
            - string
            - 'null'
          maxLength: 255
          description: The contact's last name.
          example: Doe
        user_id:
          type:
            - string
            - 'null'
          maxLength: 255
          description: An external user identifier from your application.
          example: ext_123
        unsubscribed:
          type: boolean
          description: Whether the contact should be marked as unsubscribed.
          example: false
        list_ids:
          type: array
          items:
            type: string
            format: uuid
          description: >-
            List IDs to attach the contact to. Replaces existing list
            memberships.
          example:
            - 550e8400-e29b-41d4-a716-446655440000
        properties:
          type: object
          additionalProperties:
            type:
              - string
              - 'null'
            maxLength: 255
          description: >-
            Property values to set on the contact. Keys must match existing
            property keys.
          example:
            company: Acme
    Contact:
      type: object
      properties:
        id:
          type: string
          format: uuid
          description: Unique identifier.
          example: 550e8400-e29b-41d4-a716-446655440000
        email:
          type: string
          format: email
          description: The contact's email address.
          example: john@example.com
        first_name:
          type:
            - string
            - 'null'
          description: The contact's first name.
          example: John
        last_name:
          type:
            - string
            - 'null'
          description: The contact's last name.
          example: Doe
        user_id:
          type:
            - string
            - 'null'
          description: An external user identifier from your application.
          example: ext_123
        unsubscribed:
          type: boolean
          description: Whether the contact has unsubscribed.
          example: false
        properties:
          type: object
          additionalProperties:
            type: string
          description: Custom property values. Keys are uppercased property names.
          example:
            COMPANY: Acme
            PLAN: pro
        lists:
          type: array
          items:
            $ref: '#/components/schemas/ListSummary'
          description: Lists this contact belongs to.
        created_at:
          type: string
          format: date-time
          description: When the contact was created.
          example: '2026-03-03 10:00:00'
        updated_at:
          type: string
          format: date-time
          description: When the contact was last updated.
          example: '2026-03-03 10:00:00'
    ListSummary:
      type: object
      properties:
        id:
          type: string
          format: uuid
          example: 550e8400-e29b-41d4-a716-446655440000
        name:
          type: string
          example: Newsletter
        created_at:
          type: string
          description: When the list was created.
          example: '2026-03-03 10:00:00'
        updated_at:
          type: string
          description: When the list was last updated.
          example: '2026-03-03 10:00:00'
    ErrorResponse:
      type: object
      properties:
        name:
          type: string
          description: Error type identifier.
          example: validation_error
        message:
          type: string
          description: Human-readable error message.
          example: The from address domain is not verified.
  responses:
    Unauthorized:
      description: Unauthorized — missing or invalid API key
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
          example:
            message: Invalid API key.
    NotFound:
      description: The requested resource was not found
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
          example:
            message: Not found.
    ValidationError:
      description: Validation error — invalid or missing parameters
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
          example:
            message: The email field is required.
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: >-
        API key from your SendKit dashboard. Pass it as a Bearer token in the
        Authorization header.

````