This article compares five audio-video SDKs (Agora, Twilio, Jitsi as a Service, Zoom, and 100ms) in terms of features that matter to app developers. The features are organized into core capabilities, interactive features, and audio-video features. Agora, Twilio & 100ms provide a solid balance of these features with most being built or enabled with minimal dev work. JaaS offers most features but may require some development effort for specific functions. The Zoom Video SDK is still evolving and not as feature-rich as the Meeting SDK, while the Meeting SDK provides all major features but places restrictions on customization.