---
title: "Select Extension/App (for Custom Field only)"
description: "Extension/App for Custom Fields."
url: "https://www.contentstack.com/docs/headless-cms/select-extension-app-for-custom-field-only"
product: "Contentstack"
doc_type: "guide"
audience:
  - developers
  - admins
version: "current"
last_updated: "2026-07-20"
---

# Select Extension/App (for Custom Field only)

The **Select Extension/App** allows you to add the prebuilt extension/app to your Content Type by using the Custom field. To select an extension or app, log in to your [Contentstack account](https://www.contentstack.com/login), open your stack, and perform the following steps:

1.  Go to Content Models and create a new Content Type by clicking on the “**\+ New Content Type**” button. Fill in the required details on the pop-up that comes.
2.  Once the **Content Type** is created, add the required fields along with the **Custom** field. Please note that the **Title** field is the default field for every Content Type.
3.  In the **Custom Properties** modal, add the extension/app you want under **Select Extension/Apps**.![Select\_Extension\_App\_for\_Custom\_Field\_only\_1.png](https://images.contentstack.io/v3/assets/blt2d43f51baca745a8/blt917c7b3c79f99e54/6675674e71203e2eae98f151/Select_Extension_App_for_Custom_Field_only_1.png)
4.  Select the app or extension that you want to use in your **Custom** field and click on **Proceed**.![Select\_Extension\_App\_for\_Custom\_Field\_only\_2.png](https://images.contentstack.io/v3/assets/blt2d43f51baca745a8/bltee8d3038f4724f1f/6675674f7ef09e526af421ee/Select_Extension_App_for_Custom_Field_only_2.png)
5.  Once the app/extension is added, it should be visible when you create an entry for that Content Type.

**Additional Resource**: To know more about how to add extensions and apps in Contentstack refer to our doc on [Create Custom Fields](https://www.contentstack.com/docs/developer-hub/custom-field-location).