What Businesses Should Know Before Adding Online Payments

Integrating payment gateways like Stripe, Paystack, or local mobile money rails involves solving complex operational challenges: preventing double billing, verifying payload signatures, and handling failed webhook deliveries.

1. Verifying Webhook Signatures

Webhooks alert your server that a transaction succeeded. Since webhook endpoints are public, attackers can easily mock payloads to activate services without paying. To prevent this, you must verify the signature header (e.g., Stripe-Signature or X-Paystack-Signature) using your endpoint's secret key before saving records.

2. Preventing Double Billing via Idempotency

Network interruptions can cause payment gateways to deliver the same webhook multiple times. If your server is not prepared, you risk recording duplicate payments. You can mitigate this by checking the database for the unique transaction ID before processing any state changes, ensuring transaction operations are idempotent.

3. Mobile Money API Integration

Integrating mobile money systems requires setting up automated reference sweeps and polling mechanisms. Decouple your payment interfaces using interface-driven design patterns to easily switch between payment routes.