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

# List fax custom fields

> List custom fields associated with a fax.

Provide the required fax identifier in `job_id`. A custom field whose value was cleared may remain in the response with `value: null`. Authenticate with a Bearer access token.


## OpenAPI

````yaml POST /v1/custom/field/list
openapi: 3.1.0
info:
  title: Amplify Customer API
  version: 1.0.0
  description: |-
    Canonical contract for the Amplify customer-facing API. This YAML file is
    the source of truth for Postman and Mintlify. Operations marked with
    x-amplify-validation-status: pending were migrated from the legacy Postman
    collection and must be validated before their contract is considered final.
servers:
  - url: https://api.amplify.xyz
    description: Production
  - url: https://dev-api.amplify.xyz
    description: Development
security: []
tags:
  - name: Authentication
  - name: Fax
  - name: Send Faxes
  - name: Receive Faxes
  - name: Manage Faxes
  - name: Workspace
  - name: Numbers
  - name: Contacts
  - name: Documents
  - name: Templates
paths:
  /v1/custom/field/list:
    post:
      tags:
        - Workspace
      summary: List fax custom fields
      description: >-
        Returns the custom fields associated with a fax. A cleared field may
        remain in the list with a `null` value.
      operationId: postv1CustomFieldList
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: false
              required:
                - job_id
              properties:
                job_id:
                  type: string
                  description: Unique identifier of the fax.
            example:
              job_id: 01KM4QNX8CKW47RGXAT90KB74C
      responses:
        '200':
          description: Custom fields retrieved successfully.
          content:
            application/json:
              schema:
                type: object
                required:
                  - status
                  - data
                properties:
                  status:
                    type: integer
                  data:
                    type: array
                    items:
                      type: object
                      required:
                        - id
                        - value
                      properties:
                        id:
                          type: string
                        value:
                          type:
                            - string
                            - 'null'
              examples:
                populated:
                  summary: Fax with a custom field
                  value:
                    status: 1
                    data:
                      - id: codex_validation_20260905
                        value: Validation test
                empty:
                  summary: Fax without custom fields
                  value:
                    status: 1
                    data: []
        '422':
          description: A required field is missing.
          content:
            application/json:
              schema:
                type: object
                required:
                  - status
                  - message
                properties:
                  status:
                    type: integer
                  message:
                    type: string
              example:
                status: 0
                message: The job id field is required.
      security:
        - bearerAuth: []
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer

````