Webhook Glossary
Short, plain-language definitions for the terms used across the docs and blog.
Jitter
A small random offset added to a scheduled delivery time so that many deliveries don't all land at the exact same instant. On its own it's a fine-tuning tool; paired with a minimum spacing between deliveries (cadence), it's what stops a burst of webhooks from tripping a receiver's rate limiter. See Jitter, cadence & job lifecycle.
Dead-letter queue (DLQ)
Where a job goes after it has exhausted every retry attempt without a successful delivery. A DLQ turns a silent failure into an inspectable, replayable one — instead of a webhook just disappearing, it sits in the DLQ until someone reviews and either retries or resolves it. See What is a webhook dead-letter queue.
Exponential backoff
A retry strategy where the delay before each subsequent attempt increases — typically by roughly doubling — instead of retrying at a fixed interval. It gives a struggling or temporarily-down receiver increasing breathing room rather than a tighter retry loop. See Exponential backoff vs. jitter.
Idempotency key
A caller-supplied value attached to a request so that retrying the same logical request — after a timeout, for example — doesn't create a duplicate side effect. A repeat request with a previously-used idempotency key returns the original result instead of processing it again. See Webhook idempotency keys.
SSRF (server-side request forgery)
A vulnerability where a server can be tricked into making an outbound request to an address it shouldn't reach — internal infrastructure, a cloud metadata endpoint, or localhost — because a user-controlled URL wasn't validated before the server requested it. A webhook destination field is a textbook example of user-controlled input to an outbound request. See SSRF and webhooks.
Standard Webhooks
An open specification for signing and verifying webhook payloads, using a common header shape (svix-id, svix-timestamp, svix-signature) so a receiver can verify webhooks from any compliant sender with the same verification code. See standardwebhooks.com and Verifying signatures.