Secure your postback endpoint: 6 checks that block fake conversion calls

Secure your postback endpoint: 6 checks that block fake conversion calls

Treat the postback URL as a public API. Every request is untrusted: accept only required fields and never let the caller set payout, status, or account IDs.

Use layers:
— Allowlist known network IPs when stable, and keep the list documented.
— Require a random token or HMAC signature; keep secrets server-side.
— Enforce HTTPS and reject stale timestamps or reused nonces.

Validate click ID format, offer mapping, status, and currency before processing. Make events idempotent: one event ID must not create duplicate conversions.

Log the event ID, source IP, validation result, and rejection reason—but not secrets. Alert on spikes, unknown click IDs, and repeated failures. Return generic errors to callers.

IP filtering reduces noise; authentication proves origin; validation protects data; idempotency limits replay damage. Test rejected requests before sending live traffic.