# Flex Configuration

> \[!WARNING]
>
> For Customers building HIPAA-compliant workflows with Flex UI, Customers are required to ensure that there is no PHI in any Properties of Configuration Objects. Details on Configuration Objects and Properties can be found on the official Flex UI [documentation](https://assets.flex.twilio.com/docs/releases/flex-ui/latest/overview/Config). To learn more about building for HIPAA compliance, please visit the latest requirements [here](/documents/architecting-for-HIPAA.pdf).

You can customize some aspects of Flex's appearance and behavior through configuration. There are two ways to manage Flex configuration:

* For Twilio-hosted Flex deployments (flex.twilio.com), use the [Flex Configuration REST API](/docs/flex/developer/config/flex-configuration-rest-api) to set configuration values.
* For customer-hosted Flex deployments, define configuration values in the [appConfig.js configuration object](/docs/flex/developer/config/appconfigjs) on your server, or via the [Flex Configuration REST API](/docs/flex/developer/config/flex-configuration-rest-api).