WebRTC is an open source and free project using which web browsers and mobile applications can communicate through RTC (Real-Time Communications) via simple APIs.
Project WebRTC is supported by Google, Mozilla and Opera, amongst others. Because of its amazing features it is very popular in VoIP applications now a days.
Supported Browsers & Platforms:
The main motive of WebRTC is to help building a strong RTC platform that can work across multiple web browsers or across multiple platforms. The WebRTC architecture as stated in their official website looks something like this:
You can know more about installation and use of WebRTC from their official website.