> This page is for Designer API.

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> For a complete documentation index, see https://developers.webflow.com/llms.txt.
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# Extension utilities

> Essential utilities for managing your Designer Extension's interaction with Webflow

The Designer API offers essential utilities to manage your extension's behavior and interaction with the Designer.

#### [Site information](/designer/reference/get-site-info)

Access site details and configure how your extension appears in the Designer

#### [User events](/designer/reference/events)

Subscribe to Designer events to create responsive extensions

#### [App discovery](/designer/reference/app-intents-and-connections)

Make your extension discoverable in element settings

#### [User authentication](/designer/reference/get-user-id-token)

Authenticate users with the Data API, and access Data API resources

## Best practices

#### Dynamic updates

[Subscribe to relevant events](/designer/reference/events) like when a user selects a new element to keep your extension in sync with the Designer state.

#### Appropriate sizing

[Size your extension appropriately](/designer/reference/resize-extension) with `resizeExtension()`. Too large and it dominates the UI; too small and it's hard to use.

> **Note**
>
> For a comprehensive guide to building effective extensions, check out our [Quick Start Guide](/designer/docs/getting-started-designer-extensions) and [App Setup](/designer/reference/app-structure) documentation.