---
title: "Add a client user identifier or custom identifier(s) to a user"
method: POST
path: "/identity-resolution/user-identifiers"
tags: ["Identity"]
---

# Add a client user identifier or custom identifier(s) to a user

`POST /identity-resolution/user-identifiers`

Make a call to this endpoint to associate a client user identifier or custom identifier(s) with other identifiers. A client user or custom identifier needs to be accompanied by at least one other identifier of the following types: phone, email, shopify id, klaviyo id, client user identifier, or custom identifier.

## Request body

- IdentifyRequestDto
  - `phone` string — Phone number used to associate a client user identifier or custom identifier(s) with a user. [E.164 format](https://en.wikipedia.org/wiki/E.164) is required.
  - `email` string — Email used to associate a client user identifier or custom identifier(s) with a user. There is a 100 character limit.
  - `shopifyId` string — Shopify Id used to associate a client user identifier or custom identifier(s) with a user. There is a 100 character limit.
  - `klaviyoId` string — Klaviyo Id used to associate a client user identifier or custom identifier(s) with a user. There is a 100 character limit.
  - `clientUserId` string — Client user identifier to be associated with a user through a phone, email, shopify id, klaviyo id, or custom identifier. This is a freeform field and can accept any string input. Please do NOT put shopify ids or klaviyo ids here, there are dedicated fields for those identifiers. There is a 100 character limit.
  - `customIdentifiers` CustomIdentifierDto1[] — Custom identifier(s) to be associated with a user through a phone, email, shopify id, klaviyo id, client user identifier, or another custom identifier. There is a 100 character limit.
    - `name` string, required
    - `value` string, required

## Response `202`

Request processed.

## Other responses

- `400` — Invalid parameter in request query or body
- `429` — The user has sent too many requests in a given amount of time

---

[API](https://skmtc.net/attentive/apis/attentive-api-v2.md) · [All operations](https://skmtc.net/attentive/apis/attentive-api-v2/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/attentive/attentive-api-v2/revisions/be387e501197/schema)