For the complete documentation index, see llms.txt.

Introduction to the Vennio API

Schedule on behalf of anyone — with their consent. Vennio is scheduling infrastructure for developers and AI agents: check real availability, propose the right time, and confirm a booking without anyone going back and forth.

Vennio API v1.4.0

The current stable API version is 1.4.0. All endpoints are backwards compatible within the v1 series.

What is Vennio?

Vennio is scheduling infrastructure for developers. Connect your users' calendars, query real availability across multiple people and time zones, and create bookings — all via simple REST API calls. Vennio handles the complexity of multi-provider calendar integrations (Google Calendar, Microsoft 365), conflict detection, confirmation emails, CRM sync, and webhook delivery.

Key capabilities

Availability queries — Find open slots across multiple calendars in any timezone
Direct bookings — Create calendar events and send confirmation emails in one API call
Venn Links — Shareable booking pages (like Calendly links) created programmatically
Paid bookings — Collect payments via Stripe before confirming bookings
Consent management — GDPR-compliant, fine-grained calendar access permissions
Webhook events — Real-time notifications for bookings, cancellations, and consent changes
CRM sync — Automatic Salesforce/HubSpot record creation on booking
AI-agent friendly — Structured responses, natural language descriptions, MCP support

How it works

A typical booking flow takes 3 API calls:

Query GET /v1/availability/slots to find open times
Present slots to the end-user for selection
Call POST /v1/bookings to create the booking

Vennio synchronously creates the calendar event, sends confirmation emails to both parties, and fires a booking.created webhook — all in the same response.

For paid Venn Links, the booking enters pending_payment status and returns a checkout_url. The booking confirms automatically after payment via Stripe Checkout.

Base URL

# Production
https://api.vennio.app

# Local development (run: cd api && node server.js)
http://localhost:3001

Next steps

Authentication — Get your API key
Quick Start — Make your first booking in 60 seconds
Paid Bookings — Accept payments via Stripe Connect
Platform APIs — Availability and booking endpoints