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# Extensions

## Docs

- [Extensions overview](https://buildwithfern.com/learn/api-definitions/asyncapi/extensions/overview.md): Learn about Fern's AsyncAPI extensions for generating higher-quality SDKs
- [Use audiences to filter your API](https://buildwithfern.com/learn/api-definitions/asyncapi/extensions/audiences.md): Use `x-fern-audiences` to filter to relevant operations, channels and message schemas
- [Availability](https://buildwithfern.com/learn/api-definitions/asyncapi/extensions/availability.md): Mark features as available in specific SDK versions using `x-fern-availability` extension
- [Request + response examples](https://buildwithfern.com/learn/api-definitions/asyncapi/extensions/request-response-examples.md): Add message examples to AsyncAPI specs with `x-fern-examples`. Improve SDK documentation with real-world payload examples.
- [Ignoring operations, channels, or schemas](https://buildwithfern.com/learn/api-definitions/asyncapi/extensions/ignoring-elements.md): Learn how to use x-fern-ignore to exclude specific operations, channels, or schemas from AsyncAPI SDK generation.
- [Server names](https://buildwithfern.com/learn/api-definitions/asyncapi/extensions/server-names.md): Configure custom server names in AsyncAPI specifications with `x-fern-server-name` extension. Set up production and staging server labels.
- [API Explorer control](https://buildwithfern.com/learn/api-definitions/asyncapi/extensions/api-explorer-control.md): Enable or disable the API Explorer for WebSocket channels using `x-fern-explorer`