Optional but highly recommended. SDK integration provides additional information such as browser versions, plugins and canvas data that increases the efficacy of ACP rules. If SDK integration is not used, we enforce this using Challenge action. Challenge action does not work well with Single page applications (SPA) and Native Mobile apps, so for these applications, SDK integration is mandatory. For other apps that can withstand a page refresh such as HTML pages, SDK integration is optional. We support JS SDK for web applications, and Android and iOS SDK for native mobile applications.