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.
Deepgram
Real-time and batch speech recognition API with <300ms latency. Supports 30+ languages, speaker diarization, and custom vocabulary. Nova-3 model is best-in-class for English accuracy.