Webhooks

Build-along · ~15 min at your own keyboard

A webhook is a doorbell: when something happens elsewhere (form submitted, payment received, job closed in your CRM), that service calls your URL and your workflow runs — no human noticing required. Deploy only the deterministic execution to the cloud; keep the LLM orchestration local where you can watch it.

The long version: Webhooks ↗

Mac: Mac: send a test from Terminal with curl -X POST -H 'Content-Type: application/json' -d '{"a":1}' YOUR_URL.

Windows: Windows: in PowerShell use curl.exe, not curl, which is an alias for another command. Escape the JSON quotes, or use Invoke-RestMethod.

Do this

0/5

Checkpoints

▸You should now see a handler deployed with a URL.
▸You should now see a new row in your sheet that you did not add.
▸You should now see a clear error for the malformed payload.
▸You should now see one row after the same event was sent twice, and an unsigned request rejected.

The three ways this goes wrong

The same event shows up as two rows. — Store each event's ID when you process it, and skip any ID you've already seen. Return success for the skipped duplicate so the source stops retrying.
The handler runs but no row appears. — Read the platform log. The sheet permission or the field name is usually the cause.
A bad payload is accepted silently. — Add a check that rejects missing fields with an error and writes a log line.

Share what happened

Paste the trigger source, proof the automatic run landed, the malformed-payload behavior, the duplicate-delivery result, and the signature check result (or a note that the source doesn't sign events).

Strip API keys, passwords, and tokens before you paste. Swap them for [KEY].

🔒 Don't paste confidential, personal-health, or payment info.