Glossary · AI & Agents
Vapi
Overview
What Vapi is
Vapi is a voice AI platform aimed primarily at developers. It abstracts the complex real-time infrastructure behind phone-based voice agents, letting teams focus on the conversation logic rather than the plumbing of streaming audio and model orchestration.
With Vapi you can build agents that place outbound calls and answer inbound ones, integrate with external APIs, and use custom voices and languages. It supports a large developer community and handles high call volumes.
How it works
Vapi coordinates a pipeline of speech-to-text, a large language model, and text-to-speech, and is provider-neutral so you can pick vendors for each stage. Agents are defined through configuration and API calls, with function calling and webhooks to connect tools, CRMs, and databases.
Telephony connects through providers like Twilio or Vapi's own numbers. Developers can test agents, monitor calls, and adjust prompts, voices, and logic, deploying updates without rebuilding the real-time stack.
When to use it
Vapi suits engineering teams that want programmatic control over voice agents and prefer building with APIs over a no-code flow editor. It is well-suited to custom applications where the voice agent is embedded in a larger product or workflow.
It competes closely with Retell AI, and with the open-source LiveKit stack for teams that want to self-host. Because pricing is usage-based and stacks per-minute model, transport, and voice costs, estimate total call minutes before committing.
Where we use it
Related Zen in Tech services
How our team puts Vapi to work in real projects.
FAQ
Vapi — common questions
What is Vapi used for?
Vapi is used to build voice AI agents that make and receive phone calls, powering use cases like customer support, appointment booking, lead qualification, and outbound outreach with natural, real-time conversation.
Is Vapi a no-code tool?
Vapi is developer-first, built around APIs and SDKs, though it also offers a dashboard for configuration. Teams wanting a heavier no-code builder often compare it with platforms like Retell AI.
How much does Vapi cost?
Vapi uses usage-based pricing charged per minute, and total cost also depends on the chosen speech and LLM providers plus telephony. Check current rates and provider fees against your expected call volume.
Need Vapi done right?
Book a free consultation and we’ll map the fastest, most cost-effective path for your project.
Knowledge hub
From our knowledge hub
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