27 December 2025 · 4 min read
Idempotency is not optional
Network retries will duplicate charge requests. Without idempotency keys, customers get charged twice and you find out from support.
Generate the key client-side per intent, and persist it before calling the gateway.
Trust webhooks, not redirects
Users close browsers mid-redirect. The webhook is the authoritative signal that a payment succeeded.
Verify webhook signatures, handle out-of-order delivery, and make handlers idempotent.
Reconcile continuously
Your database and the gateway will disagree occasionally. Daily automated reconciliation with an exception queue catches this within hours instead of at month end.
The discrepancies you find early are cheap. The ones you find in an audit are not.
Where to go from here
If you are weighing payment integration for an upcoming project, the useful next step is usually a short scoping conversation rather than a longer article. Bring your constraints — budget, timeline, existing systems, and the team you already have — and the decision usually resolves itself in an hour.
We run these as a fixed-scope discovery session with a written recommendation at the end, including the cases where our advice is that you do not need us.
Working on something like this?
Send us the brief. We will tell you what we would build, what we would cut, and roughly what it costs.
Talk to us