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

# Create a custom merge field



## OpenAPI

````yaml /openapi.json post /marketing/fields
openapi: 3.0.0
info:
  title: JetEmail API
  version: 1.0.0
  description: API documentation for JetEmail's transactional email service.
servers:
  - url: https://api.jetemail.com
    description: Production
security:
  - apiKeyAuth: []
tags:
  - name: Email
    description: Send transactional email
  - name: Outbound
    description: 'Outbound sending: keys, SMTP users, domains, logs, suppression'
  - name: Inbound
    description: Inbound routing, domains and forward destinations
  - name: Marketing
    description: >-
      Marketing suite: templates, audiences, contacts, broadcasts, themes,
      assets
externalDocs:
  description: Download OpenAPI Specification
  url: /openapi.json
paths:
  /marketing/fields:
    post:
      tags:
        - Marketing
      summary: Create a custom merge field
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - key
              properties:
                key:
                  type: string
                  example: companyName
                label:
                  type: string
                  example: Company name
      responses:
        '200':
          description: Created
          content:
            application/json:
              schema:
                type: object
                properties:
                  success:
                    type: boolean
                  field:
                    $ref: '#/components/schemas/MarketingField'
components:
  schemas:
    MarketingField:
      type: object
      description: >-
        A custom merge/personalization field usable as {{key}} and supplied
        per-recipient at send time.
      properties:
        id:
          type: string
        key:
          type: string
          example: companyName
        label:
          type: string
          example: Company name
  securitySchemes:
    apiKeyAuth:
      type: http
      scheme: bearer
      description: API key for account management endpoints. Use your api_ prefixed token.

````