SendBeam and Calendly

1. Calendly Trigger, with the event Event Created
2. SendBeam → Contact → Create or update
     Email       the invitee's email from step 1
     First name  the first name, if there is one
     Source      calendly
3. SendBeam → Contact → Add to list
     Contact     By email, the same expression as step 2
     List        From list, then pick the list by name

Install the SendBeam node from Settings → Community nodes (n8n-nodes-sendbeam). Adding someone who is already a contact, or already on the list, succeeds, so the workflow is safe to re-run.

Module 1: the Calendly module that watches for new invitees
Module 2: HTTP → Make a request
URL:          https://sendbeam.io/api/v1/contacts
Method:       POST
Headers:      x-api-key = sb_live_XXXXXXXX_YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY
Body type:    Raw
Content type: JSON (application/json)
Request content:
{
  "email": "{{1.email}}",
  "first_name": "{{1.first_name}}",
  "source": "calendly"
}

Replace {{1.email}} and {{1.first_name}} with the invitee's email and the name, mapped from module 1. A 409 answer means the contact already exists; route it to GET /api/v1/contacts?q= with the same address if you need the contact's id.

Trigger  Calendly's trigger for new invitees
Action   Webhooks by Zapier → POST
URL           https://sendbeam.io/api/v1/contacts
Payload type  json
Data
  email       the invitee's email
  first_name  the first name
  source      calendly
Headers
  x-api-key   sb_live_XXXXXXXX_YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Webhooks by Zapier is available on Zapier's paid plans. The SendBeam app for Zapier will replace this step with a Create Contact action once it is listed in Zapier's directory.