The open RSVP API

Create events, collect RSVPs, and fire webhooks — all with a curl-able REST API. No accounts, no SDK required.

Quickstart

Create an event with a single request — no key, no signup:

# Create an event
curl -X POST https://yupno.io/api/v1/events \
  -H "Content-Type: application/json" \
  -d '{"title":"Launch Party","eventDate":"2026-07-01T18:00:00Z"}'

# Response includes adminToken + eventToken (capability URLs)
# Fetch RSVPs (admin only)
curl https://yupno.io/api/v1/events/EVENT_TOKEN/rsvps \
  -H "Authorization: Bearer ADMIN_TOKEN"

Endpoints

POST/api/v1/eventsCreate event

GET/api/v1/events/{token}Get event

PUT/api/v1/events/{adminToken}Update

DELETE/api/v1/events/{adminToken}Delete

POST/api/v1/seriesRecurring

GET/api/v1/events/{token}/rsvpsRSVPs (auth)

POST/api/events/{token}/rsvpSubmit RSVP

No auth hassle

Yup/no uses a capability-URL model: a 32-char admin token and a 16-char event token. Hold the URL, hold the access — no users, sessions, or OAuth to manage.

Webhooks

Set webhookUrl to get a POST when guests RSVP. Slack and Discord payloads auto-format.

{ "action": "created", "event": {...}, "rsvp": { "name", "email", "attending" } }

Use it from Claude

Connect the yup/no MCP server and create themed events in natural language.

claude mcp add yupno -- npx -y yupno-mcp-server --stdio

Or remote: https://yupno.io/mcp · Bundle: download .mcpb · Machine spec: /llms.txt