Webhook Signature Verifier: Secure Event Validation

Why Signature Verification Is Non-Negotiable

Without signature checks, anyone can POST forged events to your webhook endpoint. This can trigger fake order updates, unauthorized workflow execution, or noisy incident alerts. A reliable verifier confirms that the payload was signed by the provider using your shared secret and that the body was not tampered with in transit.

Raw Body and Canonical Payload Rules

Most verification bugs happen before cryptography: middleware mutates whitespace, parses JSON too early, or encodes characters differently than the provider expects. Stripe and Slack require canonical strings that include timestamp metadata plus raw body bytes. Use our verifier to preview canonical payloads and compare against generated signatures before touching backend middleware.

Replay Protection and Secret Rotation

A valid signature can still be abused if an old request is replayed. Enforce timestamp tolerance windows and reject stale deliveries. During secret rotation, systems often need to support both current and previous secrets briefly. Our tool tests primary and fallback secrets so rollout is safe without dropping legitimate events.

Practical Debugging Workflow

Start with request construction in our Curl Generator, then verify payload integrity with this tool, and finally sanitize sensitive traces using our PII Redactor before sharing incidents. If your payload is JSON-heavy, prepare bodies in our JSON Formatter to reduce manual mistakes during QA.