Open Source Retell Alternatives

LiveKit is an open source framework and cloud platform for building AI agents that communicate through voice, video, or physical interfaces. It's aimed at developers who need production-grade infrastructure without assembling a custom stack from scratch. OpenAI built ChatGPT's Advanced Voice on it, and the platform handles over 2.5 billion calls annually.

The core idea is to cover the entire agent lifecycle in one place. You write agent logic, connect it to the speech and language models you choose, and deploy it without managing the underlying real-time infrastructure yourself. Automatic turn detection and interruption handling are built in, so agents respond naturally in conversation rather than waiting for rigid cues.

Key capabilities include:

• Open source agent framework for building and testing agents locally before deploying
• Inference gateway that connects to TTS, LLM, and STT providers (Deepgram, Google, Cartesia, and others) through a unified interface
• Telephony and SIP integrations so agents can handle phone calls alongside browser and app sessions
• Full-stack observability across every agent session, not just aggregate metrics
• LiveKit Cloud for deploying and scaling agents across regions globally, with SOC 2 Type 2, HIPAA, and GDPR compliance

LiveKit fits squarely in the AI agent platforms space but goes further than most by covering real-time media transport, not just LLM orchestration. That makes it relevant for robotics and video AI use cases, not just voice chatbots. Teams that have moved off homegrown WebSocket stacks cite the unified export interface across web and phone as a concrete reason to switch.

The self-hosted framework is free and open source. LiveKit Cloud adds managed scaling, telephony, and observability, with 1,000 free agent session minutes per month and no credit card required to start.