Vapi
Vapi, LiveKit, Retell and Pipecat differ by orchestration layer
AssemblyAI’s comparison says the four voice-agent stacks sit at different layers, with trade-offs in control, transport and STT integration.
Vapi
xAI's Grok Powers 2.5M+ Voice Agents on Vapi Platform
xAI integrates Grok as the default voice for Vapi’s 12 core agents, elevating voice AI with natural speech and emotional resonance.