Webhooks turn integrations from "keep asking" into "get told". Instead of polling an API every few seconds to check for changes, you give a provider a URL, and they call it the moment something happens. It is efficient and elegant — but only if you handle security and reliability correctly, which many implementations get wrong.
Webhooks versus polling
Polling means repeatedly asking "has anything changed?" — wasteful, slow to react, and hard on rate limits. A webhook inverts this: the provider sends an HTTP POST to your endpoint the instant an event occurs. You get near-real-time updates with no wasted requests. The trade-off is that you now run a public endpoint that must be secure and resilient.
Always verify the signature
Your webhook URL is public, so anyone could POST fake events to it. Reputable providers sign each payload with a shared secret using HMAC, and include the signature in a header. Your receiver must recompute the HMAC over the raw body with that secret and compare it to the header. If they do not match, reject the request. Skipping this is a serious security hole.
Handle retries and idempotency
Networks fail, so providers retry deliveries — which means you may receive the same event more than once. Make your processing idempotent: use the event’s unique ID to detect and ignore duplicates, so processing the same webhook twice has no extra effect. Respond quickly with a 2xx to acknowledge receipt, and do slow work asynchronously rather than making the provider wait.
Build a reliable receiver
- Verify the signature before doing anything else.
- Acknowledge fast with a 2xx; queue heavy work for later.
- Deduplicate using the event ID.
- Log everything — webhooks are hard to debug without a record.