Payment integration is one of the few pieces of a project where a small technical decision has a permanent, compounding financial effect. A 0.5% difference in transaction fees on ₹50 lakh of annual revenue is ₹25,000 a year, every year.
The main options compared
| Gateway | UPI | Domestic cards | International | Settlement |
|---|---|---|---|---|
| Razorpay | ~0–2% | ~2% | ~3%+ | T+2 (T+1 available) |
| PayU | ~0–2% | ~2% | ~3%+ | T+2 |
| Cashfree | ~0–2% | ~1.9% | ~3%+ | T+1 available |
| Stripe | Limited | ~2–3% | ~3–4% | T+3 to T+7 |
| PhonePe / Paytm | ~0–1.5% | ~2% | Limited | T+1 to T+2 |
Published rates are starting points. Volume is negotiable — once you are processing meaningful monthly value, ask for better pricing. Most businesses never ask.
Push UPI hard. It carries the lowest fees of any method in India and the highest completion rate. Making UPI the visually primary option — not one choice among six — measurably improves both margin and conversion.
What the integration actually involves
- Create an order server-side Your backend calls the gateway to create an order with the amount. Never let the browser decide the price — that is the classic tampering vulnerability.
- Open the checkout The gateway's SDK handles card entry, UPI, and 3D Secure. You never touch card data, which keeps PCI scope minimal.
- Verify the signature On success the gateway returns a payment ID and signature. Your server must verify that signature against your secret key before treating the payment as real.
- Handle the webhook The gateway also notifies your server directly. This is the authoritative source of truth — browsers close, networks drop, users navigate away.
- Reconcile Match gateway settlements against your order records regularly. Mismatches happen and are far easier to resolve within days than months.
The single most common integration bug in India: marking an order paid based only on the browser redirect. If the customer closes the tab after paying, the payment succeeds but your system never records it. Always treat the server-side webhook as authoritative, and make webhook handling idempotent so duplicate deliveries do not double-count.
Documents you will need
- PAN card — business or proprietor
- GST registration certificate
- Cancelled cheque or bank statement for the settlement account
- Business registration proof (incorporation certificate, partnership deed, or Udyam)
- A live website showing pricing, refund policy, terms, and contact details
That last point delays more applications than anything else. Gateways check that your site has a visible refund/cancellation policy and genuine contact information before approving. Publish those pages before applying.
Things that surprise first-time integrators
| Surprise | What to do |
|---|---|
| Settlement is T+2, not instant | Plan working capital accordingly |
| Refunds do not return the fee | Factor into your returns policy |
| Recurring payments need e-mandate | Separate setup; extra approval |
| Chargebacks carry a penalty | Keep delivery proof for every order |
| Some categories are restricted | Confirm eligibility before building |
| Test and live keys behave differently | Always run a small real transaction before launch |
Reducing failed payments
Payment failure rates in India are higher than most founders expect, and much of it is recoverable:
- Offer UPI, cards, net banking, and wallets — bank-side failures are common and vary by method.
- Show a clear retry path rather than a dead-end error page.
- Never clear the cart on a failed payment.
- Send a payment link by WhatsApp or SMS after a failure — this recovers a meaningful share of orders.
- Log the gateway's failure reason so you can spot systematic issues with a particular bank or method.
A failed payment is not a lost customer unless your checkout treats it that way.
Security essentials
- Keep secret keys on the server only — never in JavaScript, mobile apps, or your repository.
- Verify every signature server-side, without exception.
- Serve the whole site over HTTPS.
- Never store raw card details — use the gateway's tokenisation if you need saved cards.
- Rate-limit payment endpoints against automated card testing.
Integrating payments and want it done correctly the first time? Talk to us. See also our e-commerce cost guide, which covers how these fees affect real store margins.