Vapi
Free tierVoice agents for builders
Free tier available·All audiences·Powered by OpenAI (intelligence), Deepgram (transcriber), ElevenLabs (voice)·API available
Key strengths
Sub-500ms average latencyEnterprise-grade scalability (billions of calls)SOC 2, HIPAA, and PCI complianceAPI-native designFully managed infrastructureReal-time monitoring and observabilityBroad telephony integrations (Twilio, Vonage, Telnyx, SIP)
Free tier + paid plans
Founded 2023
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Vapi — Developer Documentation & Integration
API & SDKs Vapi is API-native, meaning every capability is accessible programmatically. Developers interact with Vapi through its REST API to configure agents, manage calls, and retrieve observability data.
Transport Protocols
- WebSockets and WebRTC for browser and app-based voice sessions
- SIP for direct integration with PBX systems and enterprise telephony infrastructure
Telephony Providers Bring your own numbers or use Vapi-managed numbers via:
- Twilio, Vonage, Telnyx
AI Pipeline Configuration Each component of the voice pipeline is configurable:
- Transcriber: Deepgram
- LLM: OpenAI
- Voice: ElevenLabs
- Model costs are passed through at cost — no markup on underlying providers
Auth & Access Control
- OAuth2 authentication
- SSO and RBAC for team and enterprise environments
- Multi-organization support (additional orgs at $20/org/mo)
Observability Real-time monitoring is built in, giving developers visibility into call performance, latency, and agent behavior.
Open Source Vapi's codebase is open source and available on GitHub (126 stars), enabling inspection, contribution, and self-review of the platform.