UNA API is application interface for UNA Apps mobile application service (getuna.app), but can also be used for other applications that require JSON interface to your Joomla content. The API uses token authentication and allows for various settings for delivering your data. It supports cache with auto-clear and allows for sending push notifications to your iOS and Android apps through UNA Apps service.
Read more https://extensions.joomla.org/browse/new/extension/mobile/mobile-apps/una-api
