In this tutorial, we will develop a web application that highlights active speakers in a group video calling application using the Agora Web SDK. The project requires basic knowledge of JavaScript, JQuery, and Bootstrap, as well as an Agora developer account. We start by setting up the HTML structure and adding CSS to match the site with an Agora-based theme. Then we add the JS code that uses the Agora Web SDK for group video calling functionality. Finally, we incorporate the main feature: highlighting any user who's speaking through a blue box shadow around their video stream by enabling the volume indicator and using the callback to report the volumes every two seconds. The finished product is available on GitHub, and a demo can be seen in action.