Vapi

Free tier

Voice agents for builders

Free tier available·All audiences·Powered by OpenAI (intelligence), Deepgram (transcriber), ElevenLabs (voice)·API available

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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

Facts verified against vapi.ai on Oct 5, 2026

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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.

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