LiveKit

LiveKit started as the open-source successor to Twilio for WebRTC: a high-performance SFU/MCU media server, SDKs in every major language, telephony bridges (SIP and PSTN), recording, and an Egress/Ingress pipeline for streaming. Over the last two years it has become the standard real-time substrate for AI voice agents — partly because OpenAI's Realtime API for Voice runs on LiveKit infrastructure, and partly because LiveKit Agents (the open-source SDK in Python and Node) handles every hard problem in voice agent development: low-latency audio, turn detection, interruption handling, telephony bridging, function/tool calls, multimodal LLM streaming (OpenAI Realtime, Gemini Live, Anthropic), and TTS/STT swapping (Cartesia, ElevenLabs, Deepgram, Whisper, OpenAI). LiveKit Cloud is the managed offering with a global edge network and clear pricing: a free tier for development, Build at $50/month for production prototyping, Ship for higher-volume teams, and Scale / Enterprise for negotiated capacity with SOC 2, HIPAA, and private deployments.