---
title: "Set custom field value"
method: PUT
path: "/v1/contacts/{contactId}/fields/{slug}"
tags: ["Custom Fields"]
---

# Set custom field value

`PUT /v1/contacts/{contactId}/fields/{slug}`

Set or overwrite a custom field value on a contact. The value type must match the field definition.

## Path parameters

- `contactId` string, required
- `slug` string, required

## Request body

- object
  - `value` unknown, required

## Response `200`

Field value set

## Other responses

- `401` — Unauthorized
- `404` — Resource not found

---

[API](https://skmtc.net/zernio/apis/zernio-api.md) · [All operations](https://skmtc.net/zernio/apis/zernio-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/zernio/zernio-api/versions/51932b099b2f/schema)