We describe the client-server architecture and browser-to-browser groupware functionality of a secure mobile business communication platform that utilizes advanced web technologies by means of HTML5 and powerful JavaScript frameworks. The design is based on a real-time, peer-to-peer multimedia communication paradigm and adopts WebRTC as basic software architecture of the communication layer. To guarantee confidentiality, integrity, and authenticity of the communication processes and to avoid the strict dependence on existing, purely TLS based solutions, it integrates a newly designed, client-centric security concept with a strict end-to-end encryption of all data flows. We elaborate on the multi-layer architecture of this new software platform that can be applied to support a variety of e-business services in a cloud environment including a heterogeneous population of mobile clients.