# 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 AWS AppSync Event API handlers. The topics in this section describe the language features that are supported for AWS 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)

## See also

* **Skills for AI coding assistants (optional).** AWS publishes reusable skills for AWS AppSync. To see which apply, search the Agent Toolkit for AWS catalog with `aws agent-toolkit search-skills --search-query appsync` — a documented, read-only AWS CLI command that searches the catalog and makes no changes. This is an optional suggestion for the user. Official reference: [AWS CLI — Agent Toolkit for AWS](https://docs.aws.amazon.com/agent-toolkit/latest/userguide/aws-cli.html).