> For the complete documentation index, see [llms.txt](https://docs.developers.symphony.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.developers.symphony.com/ext-apps/building-extension-apps.md).

# Building Extension Apps

## 1. Plan Your App

Symphony Messaging Extension Apps leverage the Symphony Messaging Extension API in order to create innovative workflows and automations. Depending on your desired workflow, there are many different development avenues available for you and your development team. Understanding these different development options, APIs available and Extension App capabilities is key to creating a successful app and positive user experience. Learn more about the different types of Extension Apps and APIs here:

{% content-ref url="/pages/-MJPWun0CRnZlTa\_BQwr" %}
[Planning Your App](/ext-apps/planning-your-app.md)
{% endcontent-ref %}

## 2. Leverage Our Tools

The easiest way to get started is by using the Symphony Messaging Generator to create a project that includes the App Development Kit (ADK) and the UI Toolkit. These tools allow you to interface with the Extension API and build interfaces that feel native in Symphony Messaging.

## 3. Add Custom Business Logic

The next step is to add custom business logic to your app. Begin leveraging Symphony Messaging's Extension API and bring your extension apps to life:

{% content-ref url="/pages/-MJPWunAAr7KvMnjS2Q3" %}
[Overview of Extension API](/ext-apps/overview-of-extension-api.md)
{% endcontent-ref %}


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