---
title: "[Set Up Your Project] - Select Extension/App (for Custom Field only)"
description: Select Extension/App (for Custom Field only)
url: https://www.contentstack.com/docs/developers/create-content-types/select-extension-app-for-custom-field-only
product: Contentstack
doc_type: how-to
audience:
  - developers
version: unknown
last_updated: 2026-03-26
---

# [Set Up Your Project] - Select Extension/App (for Custom Field only)

This page explains how to use the **Select Extension/App** option to add a prebuilt extension/app to a Content Type via the **Custom** field in Contentstack. It is intended for developers configuring content models and should be used when setting up or updating Content Types that require custom field functionality.

## 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:
- 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.
- 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.
- In the **Custom Properties** modal, add the extension/app you want under **Select Extension/Apps**.
- Select the app or extension that you want to use in your **Custom** field and click on **Proceed**.
- 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/developers/create-custom-fields).

## Common questions

### Do I need a Custom field to use Select Extension/App?
Yes. The **Select Extension/App** is used by adding it to a Content Type through the **Custom** field.

### Where do I add the extension/app selection?
In the **Custom Properties** modal, add the extension/app you want under **Select Extension/Apps**.

### When will the app/extension appear for editors?
Once the app/extension is added, it should be visible when you create an entry for that Content Type.

### Where can I learn more about adding extensions and apps?
Refer to **Additional Resource**: [Create Custom Fields](https://www.contentstack.com/docs/developers/create-custom-fields).