---
title: "Update Contact Custom Field"
method: PUT
path: "/contacts/{contactId}/custom-fields/{customFieldId}"
tags: ["contacts"]
---

# Update Contact Custom Field

`PUT /contacts/{contactId}/custom-fields/{customFieldId}`

Sets a value for the specified custom field in the contact.
If the custom field type is Text, the maximum lenght of the text is 500 characters.
Any text beyond that limit will be truncated.

This endpoint is rate limited. Use the `RateLimit-*` response headers to check current limits and remaining quota.

## Path parameters

- `contactId` string, uuid, required
- `customFieldId` string, uuid, required

## Request body

- CustomFieldBodyPut
  - `fieldType` 'Text' | 'Number' | 'Date' | 'Boolean' — Specifies the data type (text, number, date, boolean) for the custom field.
  - `values` string[]

## Response `204`

No Content

## Other responses

- `400` — Bad Request - The server cannot process the request due to a client error. Common causes: - Invalid request format - Missing required fields - Validation errors in the request data
- `401` — Unauthorized - Authentication is required or has failed. Common causes: - Missing API key - Invalid API key - Expired or deactivated API key
- `404` — Not Found - The requested resource does not exist. Common causes: - Invalid subscription ID - Subscription has been deleted - URL path contains typos or incorrect values
- `429` — Too Many Requests

---

[API](https://skmtc.net/acculynx/apis/acculynx-api-v2.md) · [All operations](https://skmtc.net/acculynx/apis/acculynx-api-v2/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/acculynx/acculynx-api-v2/versions/3a9e3886e400/schema)