Recent technological advances, such as increased CPU/GPU processing speed, along with the miniaturization of devices and sensors, have created new possibilities for integrating immersive technologies in music and performance art. Virtual and Augmented Reality (VR/AR) have become increasingly interesting as mobile device platforms, such as up-to-date smartphones, with necessary CPU resources entered the consumer market. In combination with recent web technologies, any mobile device can simply connect with a browser to a local server to access the latest technology. The web platform also eases the integration of collabora-tive situated media in participatory artwork. In this paper , we present the interactive music improvisation piece 'Border,' premiered in 2018 at the Beyond Festival at the Center for Art and Media Karlsruhe (ZKM). This piece explores the interaction between a performer and the audience using web-based applications-including AR, real-time 3D audio/video streaming, advanced web audio, and gesture-controlled virtual instruments-on smart mobile devices.