# Create a new Activity Custom Field

POST https://api.close.com/api/v1/custom_field/activity/
Content-Type: application/json

Activity Custom Fields belong to Custom Activities, and have additional attributes:

- `custom_activity_type_id` – the ID of the Custom Activity Type this Field
  should belong to.
- `required` – whether the Field will be required to publish the activity.

Reference: https://developer.close.com/api/resources/custom-fields/custom-fields-activity/create

## OpenAPI Specification

```yaml
openapi: 3.1.0
info:
  title: Close API
  version: 1.0.0
paths:
  /custom_field/activity/:
    post:
      operationId: create
      summary: Create a new Activity Custom Field
      description: >-
        Activity Custom Fields belong to Custom Activities, and have additional
        attributes:


        - `custom_activity_type_id` – the ID of the Custom Activity Type this
        Field
          should belong to.
        - `required` – whether the Field will be required to publish the
        activity.
      tags:
        - subpackage_customFieldsActivity
      parameters:
        - name: Authorization
          in: header
          description: Basic authentication
          required: true
          schema:
            type: string
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: >-
                  #/components/schemas/custom_fields.activity_create_Response_200
        '400':
          description: Bad request
          content:
            application/json:
              schema:
                description: Any type
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                description: Any type
        '404':
          description: Not found
          content:
            application/json:
              schema:
                description: Any type
      requestBody:
        content:
          application/json:
            schema:
              description: Any type
servers:
  - url: https://api.close.com/api/v1
components:
  schemas:
    custom_fields.activity_create_Response_200:
      type: object
      properties: {}
      description: Empty response body
      title: custom_fields.activity_create_Response_200
  securitySchemes:
    ApiKeyAuth:
      type: http
      scheme: basic
    OAuth2:
      type: http
      scheme: bearer

```