Try Vapi
Overview
Vapi is the voice AI platform for teams who want control over every layer of the stack. A voice agent is really a pipeline — speech to text, a language model, text to speech, and telephony — and most platforms make those choices for you. Vapi exposes all of them: model provider (GPT, Claude, Gemini, Groq), voice provider (ElevenLabs, Cartesia, Deepgram, PlayHT), telephony, and the latency tuning that determines whether a conversation feels natural or stilted.
That control is why serious voice engineering teams converge on it. Latency in voice is not a vanity metric — above roughly 800 milliseconds a caller starts talking over the agent, and the conversation degrades badly. With optimised provider pairings Vapi lands in the 500 to 600 millisecond range, and critically it gives you the knobs to get there rather than a fixed pipeline you have to accept.
The corollary is that Vapi asks more of you. Every choice it exposes is a choice you have to make correctly, and a badly configured Vapi agent will perform worse than a well-configured opinionated platform. If you do not have an engineer who will care about turn-taking behaviour and provider latency characteristics, Retell's more opinionated design will serve you better.
Key Features
Model Provider Choice
GPT, Claude, Gemini or Groq behind the same agent, so you can trade reasoning quality against latency and cost deliberately.
Voice Provider Choice
ElevenLabs, Cartesia, Deepgram, PlayHT and others, because voice quality and latency trade off differently for every use case.
Latency Tuning
Explicit control over the pipeline behaviour that determines whether a call feels like a conversation or a walkie-talkie exchange.
Telephony Included
Inbound and outbound phone numbers handled by the platform rather than wired up separately.
Function Calling and Tools
Agents call your APIs mid-conversation — checking availability, booking, looking up an account — which is what separates a useful agent from a voice FAQ.
Call Analytics and Recordings
Transcripts, recordings and analytics for reviewing what agents actually said to customers.
Pros & Cons
Advantages
- The most configurable voice platform available — every layer is yours to choose
- Competitive latency with optimised provider pairings
- Avoids lock-in to any single model or voice vendor
- Function calling makes agents genuinely useful rather than conversational
- The platform serious voice teams standardise on
Disadvantages
- Configuration burden is real — bad choices produce a bad agent
- Steeper learning curve than opinionated alternatives
- Costs stack across model, voice and telephony providers
- Requires engineering ownership rather than a business user
Pricing Plans
| Plan | Price | Key Features |
|---|---|---|
| Pay as you go | From ~$0.05 / minute | Platform fee plus your model, voice and telephony costs |
| Enterprise | Custom | Volume rates, dedicated support, compliance review |
Best Use Cases
Vapi Excels At:
- Engineering teams building voice as a core product capability
- Use cases where latency determines whether the product works
- Agents needing deep integration with internal APIs
- Teams that want to switch providers as the market moves
May Not Be Ideal For:
- Business users wanting a no-code phone agent
- Simple call deflection where an opinionated platform is faster to ship
- Teams without engineering capacity to tune the pipeline
How It Compares
Vapi vs Retell AI
Retell pairs a no-code builder with an SDK and transparent per-minute pricing; Vapi exposes everything and expects you to know what to do with it. Retell ships faster for standard use cases, Vapi goes further when voice is the product.
Vapi vs Bland AI
Bland is cheaper at high outbound volume and tightly optimised for latency; Vapi is more flexible across providers and use cases. High-volume outbound favours Bland, complex integrated agents favour Vapi.
Final Verdict
Our Recommendation
Vapi is the right platform when voice is a core capability rather than a feature. Exposing model, voice and telephony choices is what lets a team hit the latency that makes a call feel like a conversation, and function calling is what makes the agent useful once it is there. The flexibility is also the warning: every exposed knob is a decision you can get wrong, and an unconfigured Vapi agent underperforms a well-configured opinionated one. Choose it when you have an engineer who will own the pipeline, and choose Retell when you do not.