Webhooks and the public API

• The REST API creates and reads customers, jobs, invoices (drafts), payments, team members and events, with keys you create and scope yourself.
• Webhooks send a signed JSON event to an https URL you choose when a job is scheduled, completed or rescheduled, an invoice is paid, a payment is refunded, a lead arrives and so on. The full list of events, with example payloads, is on the developer docs.
• A delivery log shows every attempt, the response your server gave, and lets you replay a delivery.

It does not ship with connectors. The Zapier app and QuickBooks Online sync are planned and not available (see what is planned). Slack notifications are separate and use an incoming webhook, set up under Settings, Integrations. If you want a connector that does not exist, this is what a developer would build it on.

Create a customer from a script

Send an Idempotency-Key so a retry never creates a second customer. The key is remembered for 24 hours.

curl -X POST https://www.calspark.app/api/v1/customers \
  -H "Authorization: Bearer csk_live_..." \
  -H "Idempotency-Key: web-form-2026-10-06-0042" \
  -H "Content-Type: application/json" \
  -d '{"first_name":"Dana","last_name":"Whitaker","email":"dana@example.com"}'

What a webhook delivery looks like

Every delivery is a POST with the same envelope. data.object is the job, invoice or customer, and previous_attributes holds what changed.

{
  "id": "evt_...",
  "type": "job.completed",
  "api_version": "...",
  "created": 1760000000,
  "company_id": "...",
  "data": {
    "object": { "id": "5081", "status": "completed", "...": "..." },
    "previous_attributes": { "status": "in_progress" }
  }
}

Two ideas people use first: send each completed job to a spreadsheet (guide), or post a message to your own chat tool when a large invoice is paid.