> For the complete documentation index, see [llms.txt](https://learn.squirrel365.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://learn.squirrel365.io/squirrel-addon-documentation/building-an-addon.md).
# Building an addon
## What you’ll need
If you want to create an addon you will need will need to create and host a web application. We provide sample code to get you started in the following languages:
| [](/squirrel-addon-documentation/squirrel-helper-library/angular/getting-started.md) | [](/squirrel-addon-documentation/squirrel-helper-library/react.md) | [](/squirrel-addon-documentation/squirrel-helper-library/javascript/getting-started.md) |
| :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: |
In this guide will cover the following topics, providing code examples where appropriate.
1. [Communicating ](/squirrel-addon-documentation/building-an-addon/communication.md)with Squirrel and advising when the addon is ready to receive data
2. Defining a [default state](https://learn.squirrel365.io/squirrel-addon-documentation/pages/t9VAveCwtB3eQR9XIBKT#defaultstate.json)
3. Squirrel lifecycle hooks and [events](/squirrel-addon-documentation/squirrel-helper-library/javascript/events.md)
4. [Receiving data](/squirrel-addon-documentation/squirrel-helper-library/angular/events/onpropertychange.md) from Squirrel
5. [Sending data](/squirrel-addon-documentation/squirrel-helper-library/javascript/methods/sendtosquirrel.md) to Squirrel
6. Building a [property panel](/squirrel-addon-documentation/building-an-addon/property-panel/property-panel-elements.md)
Alternatively you can download the sample projects and review them. We have packed them full of comments to explain how things work.
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