---
title: "Adds Customer Additional Fields to a Customer."
method: POST
path: "/customers/{id}/fields.json"
tags: ["Customer Additional Fields"]
---

# Adds Customer Additional Fields to a Customer.

`POST /customers/{id}/fields.json`

## Request

- Base URL: `https://api.jumpseller.com/v1`
- URL: `https://api.jumpseller.com/v1/customers/{id}/fields.json`
- Auth: one of:
  - HTTP basic
  - API key in query parameter `login` and API key in query parameter `authtoken`
  - OAuth 2
    - Authorization code: `https://accounts.jumpseller.com/oauth/authorize`
    - Token URL: `https://accounts.jumpseller.com/oauth/token` scopes: `write_customers`

Sets the value of a Checkout Custom Field for the Customer. For `selection` fields the value must be one of the field options. A Customer can only have one value per Checkout Custom Field.

## Path parameters

- `id` integer, required

## Request body

- CustomerAdditionalFieldEdit
  - `customer_additional_field` CustomerAdditionalFieldEditFields
    - `value` string, required: Value of the Customer Additional Field
    - `checkout_custom_field_id` integer, required: Unique identifier of the Checkout Custom Field

## Response `200`

OK

- CustomerAdditionalField
  - `customer_additional_field` CustomerAdditionalFieldFields
    - `id` integer: Unique identifier of the Customer Additional Field
    - `label` string: Label of the Customer Additional Field
    - `value` string: Value of the Customer Additional Field
    - `area` string: Area of the Customer Additional Field
    - `customer_id` integer: Unique identifier of the Customer
    - `checkout_custom_field_id` integer: Unique identifier of the Checkout Custom Field

## Other responses

- `400`: Missing `customer_additional_field` body or invalid JSON.
- `404`: Customer or Checkout Custom Field not found, value missing or not a valid option, value already set for this Customer, or it could not be saved.

## Changes

- **2026-10-15** `53dc9f2c1329`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/jumpseller/apis/jumpseller-api/changes/customers/:id/fields.json/post.md)

---

[API](https://skmtc.dev/jumpseller/apis/jumpseller-api.md) - [All operations](https://skmtc.dev/jumpseller/apis/jumpseller-api/llms.txt) - [OpenAPI document](https://skmtc.dev/jumpseller/apis/jumpseller-api/revisions/09f991a20d74?raw)