Short answer: Use a webhook when the source can push a trustworthy event. Use polling when the source exposes no event endpoint or when periodic reconciliation is required. In both cases, make processing repeat-safe.

When does a webhook fit?

A webhook can start the workflow soon after an external event. It suits form submissions, payment notices, and application events when the sender supports retries and signature verification.

Give the endpoint a clear authentication rule. Validate the payload before changing data. Return the expected response quickly when the sender has a short timeout.

When is polling safer?

Polling fits systems with no webhook support or weak event delivery. The workflow can ask for records changed since a stored cursor or timestamp. It can also repair missed events.

Use a narrow query and a stored checkpoint. Respect the API rate limit. Stop or alert when the source returns the same page repeatedly.

How do latency and cost differ?

Webhooks usually avoid empty requests, but they need a reachable endpoint and sender configuration. Polling is easier to start in a private network, but it spends requests when no data changed.

Measure the actual interval and record volume. A five-minute poll of a busy account may be cheaper than a complex event bridge. A five-minute poll of a quiet account may be wasteful.

What reliability checks are required?

Store an event ID or source cursor. Reject duplicates without losing the original result. Log rejected signatures, invalid payloads, and API response codes.

Use the trigger comparison guide for setup details. For endpoint verification and credentials, see the webhook security guide.