# Runtime features
<a name="runtime-features-overview"></a>

The APPSYNC\_JS runtime environment provides features and utilities to help you work with data, and write functions and Amazon AppSync Event API handlers. The topics in this section describe the language features that are supported for Amazon AppSync Event APIs.

**Topics**
+ [Supported runtime features](runtime-supported-features.md)
+ [Built-in utilities](built-in-util.md)
+ [Built-in modules](built-in-modules.md)
+ [Runtime utilities](runtime-utilities.md)