> For the complete documentation index, see [llms.txt](https://docs-en.yoctol.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-en.yoctol.ai/advanced-settings/extension.md).

# Extension

### Introduction

Extension is an advanced function for Messenger platform.

When a button’s hyperlink is connected with a website, you can select the prompt action to be an “extension”. Then when a customer clicks on the button, a website will be displayed directly on the current tab as an extension. This will not open any new windows or new tabs. 

{% hint style="success" %}
When using “Extension” function, the linked website only needs support for mobile devices. There’s no need for an extra desktop version of the website.
{% endhint %}

![](/files/-LnpyugSOq9e4lhtvnpt)

![](/files/-LnpzLphZIDUmLHip-8H)

{% hint style="info" %}
Currently, websites need to meet the standards of the Messenger Extension SDK in order to be used as extension windows.
{% endhint %}

For more detail and official documentation, visit <https://developers.facebook.com/docs/messenger-platform/guides/chat-extensions><br>