Vapi
Developer API for building customizable voice AI agents
About
Vapi is the developer-first voice AI platform teams use to build phone agents without assembling the STT-LLM-TTS pipeline themselves. It's model-agnostic by design: swap Deepgram for Whisper, GPT-4 for Claude, ElevenLabs for Cartesia through configuration, with Squads orchestrating multi-assistant handoffs in a single call and a Composer that generates agent configs from natural language. Pricing is layered — $0.05/min platform fee plus passthrough for transcription, inference, speech synthesis, and telephony, landing around $0.07-0.25/min all-in, with $10 in free credits to start. The company raised a $50M Series B led by Peak XV. Strengths: maximum provider flexibility, solid observability (evals, simulations, monitoring), 99.9% reliability claims. Limits: it's developer-only, total cost is hard to predict across vendors, HIPAA costs $2,000/mo extra, and the visual Workflows product was retired in August 2026.
What it can do
- Model-agnostic voice pipeline; inbound and outbound calling; Squads multi-agent handoffs; function calling and tool use; call recording and transcription; low-latency architecture.
Setup
Create account, configure assistant (STT/LLM/TTS providers), provision phone numbers, set webhooks and tools, test with free credits.
Prerequisites
Engineering capacity; telephony provider account or Vapi numbers; API keys for chosen model providers.
Use cases
Works with
Trust score — 7/10
Scored 7/10 (verified tier, metrics-v1). Evidence: Platform fee $0.05/min + provider passthrough verified across airyzing, cekura, dasha reviews; typical all-in $0.07-0.25/min; $50M Series B led by Peak XV reported; model-agnostic STT/LLM/TTS swapping verified; Squads multi-agent handoffs and Composer verified; $10 free credits; Limitation: developer-only, unpredictable total cost, HIPAA $2K/mo add-on, Workflows retired Aug 2026.
Sources
Every fact above was checked against these sources. Where a claim comes from the provider and couldn't be independently verified, the text says so.