Glossary

Webhook

A webhook is a push-notification mechanism between services: instead of constantly asking "any news?" (polling), an external service sends an HTTP POST request to your URL when an event occurs. More efficient and simpler than polling.

Examples

Stripe sends payment.succeeded to your endpoint — you activate a subscription
GitHub sends a push event — your CI triggers a build
The Telegram Bot API sends a new message to your webhook URL

Security

The external service signs the request body with a secret key (HMAC-SHA256). Your handler verifies the signature before taking any action — to confirm the request genuinely came from the trusted source, not an attacker.

Reliability

A webhook handler must respond quickly (200 OK) and push real work to a queue — otherwise the external service may consider delivery failed and retry the request.