UPI and payment gateway integration in mobile apps: what founders should know

In India, if your app cannot take a UPI payment, you have already lost a large share of your customers. UPI is how most people pay for most things. But adding payments to an app is more than pasting a button. Money moves through banks, networks and apps that you do not control, and things go wrong in small, awkward ways.

This guide explains how payments work in an Indian app, how to choose a gateway, how to handle failures, and what founders usually get wrong. It is written for non-technical readers, with the technical points spelled out clearly.

The payment options your users expect

• UPI. Pay through any UPI app such as Google Pay, PhonePe or Paytm, by QR code, UPI ID or an app intent on the phone.
• Cards. Debit and credit cards, including saved cards under the tokenisation rules.
• Net banking. Still used by a meaningful group of customers.
• Wallets. Popular for small, frequent payments.
• Cash on delivery (COD). Common in e-commerce and food delivery, but it needs care with fake orders and returns.
• EMI and pay later. Useful for higher-value purchases.

Start with UPI, cards and net banking. Add wallets, EMI and COD when your numbers justify them.

Payment gateway or direct integration?

A payment gateway is a service that connects your app to banks and payment methods so you do not have to build each connection yourself. For almost every startup, using a gateway is the right choice. Well-known Indian gateways include Razorpay, Cashfree, PayU, CCAvenue and PhonePe's business solution, among others. You apply for a merchant account, complete KYC and receive keys that your app uses.

What to compare:

Factor	What to look for
Fees	Transaction rates by method, setup or annual fees, and charges for refunds
Settlement time	How quickly money reaches your bank account
Success rate	How reliably payments complete, especially on UPI
Developer tools	Good documentation, SDKs for your framework, test mode
Features you need	Subscriptions, split payments, payouts, invoices, international cards
Support and onboarding	How quickly you can go live and how responsive they are

Check each gateway's current pricing and onboarding terms directly, because these change.

How a payment flows

1. The customer taps Pay in your app.
2. Your server creates an order with the gateway and receives an order ID. The amount is decided on the server, never in the app.
3. The app opens the gateway's payment screen with that order.
4. The customer pays using UPI, card or another method.
5. The gateway tells your server the result through a secure callback, called a webhook.
6. Your server verifies the signature, marks the order as paid and updates the app.

The key rule is that your server decides whether an order is paid, based on the gateway's confirmation. Never trust only what the phone says. A user can tamper with the app but cannot forge a signed message from the gateway.

Handling the awkward cases

This is where good apps and bad apps part ways.

Payment pending

UPI payments sometimes stay "pending" for a while, especially when the bank or network is slow. Do not tell the customer it failed, and do not let them pay again blindly. Show a clear pending state, check the status with the gateway, and update the order as soon as the final result arrives.

Money debited but order not confirmed

This is the single most upsetting experience for a customer. It happens when the app loses connection after the bank debits the account. Webhooks and a regular status check fix it automatically, so the order is confirmed or the money is refunded without the customer chasing you.

Double payments

Use unique order IDs and ignore duplicate confirmations. Make the same webhook safe to receive twice.

Failed payments

Explain what happened in plain words and let the customer retry with a different method in one tap. Keep their cart.

Refunds

Give your support team an admin screen to issue full or partial refunds and show the status. Tell customers how long a refund takes. Refund timelines depend on banks and methods.

Security and compliance basics

• Never store card numbers or CVV yourself. The gateway handles card data so you stay out of the heaviest compliance burden.
• Keep secret keys on the server, never inside the app.
• Verify webhook signatures before trusting any payment message.
• Log every payment event so you can answer a customer or an auditor.
• Follow the rules for card storage (tokenisation) if you offer saved cards.
• Handle personal data lawfully. See our DPDP and app security checklist.

Business and tax matters to plan for

You will need a registered business or proprietorship and a bank account to open a merchant account, along with KYC documents. GST, invoices and reconciliation matter as soon as volume grows, so choose a gateway that gives clean reports and plan how your accounts team will match payments to orders. Speak to your accountant early about GST on fees and on your own sales.

Testing before you go live

• Use the gateway's test mode for success, failure and pending cases.
• Test on real phones with real UPI apps once live, using small amounts.
• Test a dropped connection in the middle of a payment.
• Test refunds and duplicate callbacks.
• Check the experience on slower phones and networks.

Frequently asked questions

How much does a gateway charge?

Typically a percentage of each transaction, varying by payment method, with some gateways charging extra for certain features. Compare current rates directly on each provider's website.

Can I accept UPI without a gateway?

You can use a personal or business QR, but you lose automatic confirmation, reconciliation and refunds. It does not scale beyond very small volumes.

Can an app accept international payments?

Yes, with gateways that support international cards and currencies, subject to extra approvals and fees.

Need payments in your app?

We integrate gateways, wallets and subscriptions into mobile apps with proper failure handling and admin tools for refunds and reports. See our mobile app development services, or tell us what you are building and we will advise on the right payment setup.