Twilio Video lets you build real-time video and HD audio applications using WebRTC and cloud infrastructure. Twilio Video

WebRTC is a free, open project that provides browsers and mobile applications with Real-Time Communications (RTC) capabilities via simple APIs. The WebRTC components have been optimized to best serve this purpose.

For more personal conversations, replace emojis with actual body language, put a face to a voice & help people make a real connection with video calling all thanks to the Sinch sdk. sinch (video) is one of the many integrations made avaiable with the sinch sdk.

The OpenTok iOSSDK lets you use OpenTok-powered video sessions in apps you build for iPad, iPhone, and iPod touch devices. The best way to learn how to use the OpenTok iOSSDK is to follow the OpenTok Basic Video Chat tutorial: via its parent site.

QuickBlox (VideoChat) SDK client library works with input sources (camera, microphone), codecs, compression and then the data is streamed peer-to-peer between end users. This way video calling doesn't impact the server much so the system is highly scalable. Server however enables the handshake between end users before streaming starts to take place and also it resolves NAT traversal in case configuration of networks and firewalls between end users makes call impossible otherwise. This is done with the help of QuickBlox STUN/TURN server.

Agora video voice allows you add implements real-time high quality video chat into any application. Agora video voice includes all the development tools and cloud infrastructure needed for mobile, web, and desktop applications.

Agora Signaling is a real-time voice and video, and interactive streaming platform for mobile and web.