Headline rates are the least important number. Settlement timing, failure handling and reconciliation are what you will live with.
Every gateway publishes a rate card, and every comparison article ranks them by it. In practice the headline rate is close to irrelevant, because it applies to a payment method that may be a small share of your transactions.
Your mix decides your rate
UPI typically costs close to nothing. Domestic cards sit around two per cent. International cards and EMI cost considerably more. A business taking 80% of payments over UPI has an effective rate nowhere near the advertised card rate, so compare gateways against your own mix rather than a generic table.
Settlement timing is a cash-flow decision
T+2 and T+3 are not the same for a business running on thin working capital. Ask about the rolling reserve too — some gateways hold a percentage for months against chargebacks, which is money you cannot use.
Failure handling is where integrations go wrong
The success path is easy and everyone tests it. What separates a solid integration from a fragile one is what happens when a payment times out, when a webhook arrives twice, or when a customer closes the browser mid-redirect. If those are not handled, you will eventually either double-charge someone or lose an order that was actually paid for.
- Verify every payment server-side, never trust the client
- Check webhook signatures on arrival
- Make webhook handling idempotent so retries are safe
- Give the order a state machine that cannot get stuck between states
Reconciliation
At month end someone has to match the settlement file against your orders. If the integration does not store the gateway's own transaction reference against each order, that reconciliation is manual forever. It costs nothing to store it at build time.