Create a custom contact field

POST/api/v1/contact-fields

POST /contact-fields

curl -X POST 'https://www.unitpost.com/api/v1/contact-fields' \
  -H 'Authorization: Bearer YOUR_API_KEY' \
  -H 'User-Agent: my-app/1.0' \
  -H 'Content-Type: application/json' \
  -d '{
    "key": "plan",
    "label": "Plan",
    "type": "text"
  }'

Response · 201

{
  "object": "contact_field",
  "id": "id_123",
  "key": "string",
  "label": "string",
  "type": "text",
  "default_value": "string",
  "position": 0,
  "created_at": "2026-01-01T00:00:00.000Z",
  "updated_at": "2026-01-01T00:00:00.000Z"
}

Define a new typed custom field that can then be set on any contact and used as a template variable (e.g. plan, signup_date). The key and type are fixed once created — rename the key later with Rename a custom field's key, or change the label with Update a custom contact field. See existing fields via List custom contact fields. Requires the contacts:write capability.

Request body4 fields

Field	Type	Description
`key`required	string	—
`label`required	string	—
`type`	enumtext \| number \| boolean \| date	—
`default_value`	object	—

Response · 201 fields9 fields

Field	Type	Description
`object`required	string	—
`id`required	string	—
`key`required	string	—
`label`required	string	—
`type`required	enumtext \| number \| boolean \| date	—
`default_value`required	object	—
`position`required	number	—
`created_at`required	string	—
`updated_at`required	string	—

201401409422

Create a custom contact field

Create a custom contact field

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