---
title: "Add User Properties"
method: POST
path: "/api/add_user_properties"
---

# Add User Properties

`POST /api/add_user_properties`

This API allows you to attach custom properties to any identified users from your servers, such as Sign Up Date (in [ISO8601 format](https://help.heap.io/heap-administration/administration-faqs/what-format-do-i-use-to-send-time-as-a-data-type-into-heap/)), Total # Transactions Completed, or Total Dollars Spent. Note that Heap will create a new property if it doesn’t already exist, and will overwrite the previous property if one already exists with the same name.

Currently, `heap.AddUserProperties` calls cannot be named all casings of id (ID,Id,iD,id) as it clashes with internal variables.

Our Looker Actions integration allows you to quickly import property data into Heap. See the  [Looker Actions Integration guide](https://help.heap.io/integrations/other/looker-actions-integration/) to learn more.

## Request body

- object
  - `app_id` string, required — The environment ID of your Main Production project.
  - `identity` string, required — An identity, typically corresponding to an existing user. If no such identity exists, then a new user will be created with that identity. Case-sensitive string, limited to 255 characters.
  - `properties` string, json — An object with key-value properties you want associated with the user. Each key and property must either be a number or string with fewer than 1024 characters.

## Response `200`

200

- object

## Other responses

- `400` — 400

---

[API](https://skmtc.dev/heap/apis/server-side-api.md) · [All operations](https://skmtc.dev/heap/apis/server-side-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/heap/server-side-api/revisions/6cb04521d6fa/schema)