Vapi
Full-stack platform for building, testing, and deploying voice AI agents. Handles real-time telephony, multi-provider LLM routing, interruption detection, and call analytics. Most-adopted voice agent infrastructure in production.
Retell AI
Platform for building production voice agents with sub-800ms latency end-to-end. Handles telephony, turn-taking, backchannels, and interruptions natively. Strong on call reliability and HIPAA compliance for healthcare use cases.