weMessage works by using Apple's developer tools that hook into the Messages app, as well as by turning on Accessibility features that will perform the message sending. There was zero reverse engineering involved in the creation of this app, so all messages being sent are legitimate. In addition, I believe this implementation is fair, as you still need to have an Apple device to use iMessage, but it is merely being extended to all devices.According to the developer, all iMessage features are supported, including group chats, attachments, notifications, Do Not Disturb, content blocking, and more, with notifications enabled by sending messages to the Google Firebase platform.