Vapi
Vapi is a San Francisco-based voice AI platform that lets developers build real-time, low-latency voice agents over phone, web, and SIP. It orchestrates three modular components — a transcriber (STT), an LLM, and a voice (TTS) — into a sub-700ms voice-to-voice pipeline, with first-class support for tools/function calling, multi-agent squads, outbound campaigns, persistent sessions, structured outputs, recording artifacts, evaluation scorecards, and a full REST API plus official SDKs in TypeScript, Python, C#, Ruby, PHP, and client SDKs for Web, React Native, iOS, and Python. Vapi is a Y Combinator company.
Vapi publishes 15 APIs on the APIs.io network, including Analytics API, Assistants API, Calls API, and 12 more. Tagged areas include AI, Voice AI, Voice Agents, Conversational AI, and Telephony.
The Vapi catalog on APIs.io includes 1 event-driven AsyncAPI specification, 1 JSON-LD context, and 3 Spectral governance rulesets.
Vapi’s developer surface includes changelog, CLI, authentication, developer portal, documentation, getting-started guide, signup flow, and 57 more developer resources.
Kin Score
APIs 15
Individual APIs this provider publishes, each with its own machine-readable definition.
Vapi Analytics API
Analytics endpoints.
Vapi Assistants API
Assistants endpoints.
Vapi Calls API
Calls endpoints.
Vapi Campaigns API
Campaigns endpoints.
Vapi Chats API
Chats endpoints.
Vapi Eval API
Eval endpoints.
Vapi Files API
Files endpoints.
Vapi Insight API
Insight endpoints.
Vapi Observability/Scorecard API
Observability/Scorecard endpoints.
Vapi Phone Numbers API
Phone Numbers endpoints.
Vapi Provider Resources API
Provider Resources endpoints.
Vapi Sessions API
Sessions endpoints.
Vapi Squads API
Squads endpoints.
Vapi Structured Outputs API
Structured Outputs endpoints.
Vapi Tools API
Tools endpoints.
Scroll for all 15
Postman Collections 15
Ready-to-run Postman collections for exercising this provider's APIs.
Vapi Analytics API
POSTMANVapi Assistants API
POSTMANVapi Calls API
POSTMANVapi Campaigns API
POSTMANVapi Chats API
POSTMANVapi Eval API
POSTMANVapi Files API
POSTMANVapi Insight API
POSTMANVapi Phone Numbers API
POSTMANVapi Provider Resources API
POSTMANVapi Sessions API
POSTMANVapi Squads API
POSTMANVapi Structured Outputs API
POSTMANVapi Tools API
POSTMANScroll for all 15
Open Collections 15
Open, tool-agnostic API collections (OpenAPI-derived and Bruno).
Vapi Analytics API
OPEN COLLECTIONVapi Assistants API
OPEN COLLECTIONVapi Calls API
OPEN COLLECTIONVapi Campaigns API
OPEN COLLECTIONVapi Chats API
OPEN COLLECTIONVapi Eval API
OPEN COLLECTIONVapi Files API
OPEN COLLECTIONVapi Insight API
OPEN COLLECTIONVapi Observability/Scorecard API
OPEN COLLECTIONVapi Phone Numbers API
OPEN COLLECTIONVapi Provider Resources API
OPEN COLLECTIONVapi Sessions API
OPEN COLLECTIONVapi Squads API
OPEN COLLECTIONVapi Structured Outputs API
OPEN COLLECTIONVapi Tools API
OPEN COLLECTIONScroll for all 15
Arazzo Workflows 8
Multi-step API workflows described with the Arazzo specification.
Vapi Assistant Outbound Call End to End
Create an assistant, provision a Vapi phone number, place an outbound call, and poll until it ends.
ARAZZOVapi Build a Multi-Assistant Squad
Create two specialized assistants and assemble them into a squad that can hand calls between them.
ARAZZOVapi Outbound Call Then Cost Analytics
Place an outbound call, poll it to completion, then query call analytics for cost and duration.
ARAZZOVapi Create and Verify Assistant
Create a voice AI assistant and read it back to confirm it was provisioned.
ARAZZOVapi Create Function Tool and Attach to Assistant
Create a custom function tool and attach it to a freshly created assistant.
ARAZZOVapi File-Backed Knowledge Base Assistant
Upload a file, build a query tool knowledge base from it, and create an assistant that uses it.
ARAZZOVapi Import Twilio Number and Bind Assistant
Create an assistant and import an existing Twilio number that routes inbound calls to it.
ARAZZOVapi Squad Outbound Call
Build a two-assistant squad, place an outbound call to it, and poll until the call ends.
ARAZZOScroll for all 8
MCP Servers 1
Model Context Protocol servers that expose these APIs to AI agents.
vapi-ai-mcp.yml
MCP SERVERPricing Plans 1
Published pricing tiers and plan structures.
Rate Limits 1
Documented rate limits and quota policies.
Vapi Ai Rate Limits
RATE LIMITSFinOps 1
Cost, billing, and metering signals for API financial operations.
Vapi Ai Finops
FINOPSFeatures 16
Notable capabilities this provider offers.
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Event Specifications 1
AsyncAPI definitions for this provider's event-driven and streaming APIs.
Vapi Realtime API (WebSocket Transport + Server URL Events)
AsyncAPI description of Vapi's realtime surfaces: 1. The WebSocket Transport (`wss://api.vapi.ai/{callId}/transport`) used to stream binary audio and JSON control messages to an...
ASYNCAPISemantic Vocabularies 1
JSON-LD contexts and semantic vocabularies used across these APIs.
Vapi Ai Context
JSON-LDSpectral Rules 3
Spectral governance rulesets for linting and validating these APIs.
JSON Schema 13
Standalone JSON Schema definitions for this provider's data models.
Vapi Assistant
JSON SCHEMAVapi Call
JSON SCHEMAVapi Campaign
JSON SCHEMAVapi Chat
JSON SCHEMAVapi Eval
JSON SCHEMAVapi File
JSON SCHEMAVapi Insight
JSON SCHEMAVapi ByoPhoneNumber
JSON SCHEMAVapi Scorecard
JSON SCHEMAVapi Session
JSON SCHEMAVapi Squad
JSON SCHEMAVapi StructuredOutput
JSON SCHEMAVapi FunctionTool
JSON SCHEMAScroll for all 13
JSON Structure 13
JSON Structure definitions describing this provider's data shapes.
Vapi Assistant Structure
JSON STRUCTUREVapi Call Structure
JSON STRUCTUREVapi Campaign Structure
JSON STRUCTUREVapi Chat Structure
JSON STRUCTUREVapi Eval Structure
JSON STRUCTUREVapi File Structure
JSON STRUCTUREVapi Insight Structure
JSON STRUCTUREVapi Phone Number Structure
JSON STRUCTUREVapi Scorecard Structure
JSON STRUCTUREVapi Session Structure
JSON STRUCTUREVapi Squad Structure
JSON STRUCTUREVapi Structured Output Structure
JSON STRUCTUREVapi Tool Structure
JSON STRUCTUREScroll for all 13
Examples 13
Example request and response payloads for these APIs.
Vapi Assistant Example
EXAMPLEVapi Call Example
EXAMPLEVapi Campaign Example
EXAMPLEVapi Chat Example
EXAMPLEVapi Eval Example
EXAMPLEVapi File Example
EXAMPLEVapi Insight Example
EXAMPLEVapi Phone Number Example
EXAMPLEVapi Scorecard Example
EXAMPLEVapi Session Example
EXAMPLEVapi Squad Example
EXAMPLEVapi Tool Example
EXAMPLEScroll for all 13
Security Posture 3
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Agentic Access 1
Recommended x-agentic-access execution contracts for AI agents.
Resources
Get Started 3
Portal, sign-up, and the first successful call
Documentation 5
Reference material describing how the API behaves
Agent Surfaces 4
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 16
Pagination, idempotency, versioning, errors, and events
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Build 18
SDKs, sample code, and the tooling you integrate with
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Access & Security 4
Authentication, authorization, and security posture
Operate 5
Status, limits, changes, and where to get help
Commercial 6
Pricing, plans, and the legal terms of use
Company 3
The organization behind the API