QR Code Crypto Payments: How They Work and What to Check
How QR code crypto payments work, what the QR actually contains and what customers should check after scanning. A practical guide for USDT and TRX on TRC20.
QR code crypto payments let a customer scan a code with their wallet app instead of copying a long address by hand. It cuts typing errors and makes it easy to pay from a phone while the payment page is open on a laptop. This guide explains what the QR code actually carries, what the customer still needs to check after scanning, and how to use QR codes correctly as a merchant.
What a QR code is for
A TRON address is 34 characters long and starts with T. Typing it or moving it between devices invites mistakes. A QR code turns that text into an image a camera can read. The customer:
- opens the payment page on a computer,
- taps "Send" or "Scan" in their phone wallet,
- scans the code, and the address field fills in.
Address format and validation are covered in TRC20 address format and validation.
What the MercanPay QR code contains
This matters, because systems put different data into QR codes. The QR code on the MercanPay payment page contains only the invoice's payment address. The amount and coin are not encoded.
There's a practical reason for that. Wallet apps don't interpret amount-and-token QR formats consistently, while an address-only code works the same way in nearly every TRON-compatible wallet and exchange app.
So after scanning, the customer:
- picks the coin themselves (USDT or TRX, whichever the invoice shows),
- enters the amount themselves, which they can copy with the button next to "Send exactly" on the payment page.
Tapping the QR code enlarges it, which helps on small screens or when scanning from a distance. Other page features are covered in Hosted crypto payment page features.
What the customer should check after scanning
The QR code removes address typos. The customer still has three checks to make, and they're worth passing on as a short note.
1. Network: TRON (TRC20)
Some wallets and exchanges hold the same coin on several networks. For USDT, the network must be TRON (TRC20), because USDT sent on another network won't reach the invoice. See Crypto sent to the wrong network?.
2. Coin
If the invoice asks for USDT, send USDT, and if it asks for TRX, send TRX. A different token sent to the same address doesn't complete the payment.
3. Amount
The amount must match the payment page exactly. Some exchanges subtract their withdrawal fee from the amount sent, which leaves the invoice underpaid; the customer can then send the rest to the same address. See Handling underpayments and overpayments.
Once the payment is sent, the page updates by itself. First "Payment detected · confirming" appears with a confirmation counter, then "Payment received" after 20 confirmations, usually about a minute later.
Using QR codes as a merchant
Every invoice has its own QR code
MercanPay creates a separate payment address for every invoice, so every QR code is different. This is what lets each incoming payment match its invoice automatically.
The consequence: printing one QR code and taping it next to the till is not the right use. Payments to an expired invoice's address are still credited, but tracking which customer and order they belong to gets messy, and late payments on USD-priced invoices are re-priced. MercanPay doesn't offer a static, reusable QR code or a POS device.
In-person sales
- When the customer is ready, create a new invoice in the panel. Create your first crypto invoice walks through it.
- Open the payment page on your tablet or laptop.
- Ask the customer to scan the QR code with their phone.
- Wait for the "Payment received" screen.
A short validity, such as 30 minutes, makes sense here.
Remote sales with a payment link
Online, the QR code is secondary. A customer who opens your link on their phone can't scan a code on the same screen, so they use the copy buttons for the address and amount instead. Link tips are in Crypto payment links for Telegram and Instagram sellers.
QR safety
- Take the QR code only from the payment page. An image forwarded in a chat could have been altered. Send customers the payment link, never a QR screenshot.
- Compare the start and end of the scanned address, a good habit against clipboard-swapping malware; see Address poisoning attacks.
- A screenshot is not proof of payment. Rely on the payment page status or your panel; see Fake crypto payment screenshot scams.
FAQ
Why doesn't the amount fill in when I scan?
The MercanPay QR code contains the address only, for wider wallet compatibility. Copy the amount with the button on the payment page.
Can I reuse one QR code for several customers?
Not recommended. Each invoice has its own address, so create a new invoice per customer and order.
The customer opened the page on their phone. How do they scan?
They don't need to. They copy the address and amount with the buttons and paste them into their wallet.
Which wallets can read the QR code?
Most wallet and exchange apps that support TRON addresses can read an address QR code. Make sure the customer picks the TRON (TRC20) network.
Get started with MercanPay
Accept USDT and TRX with a customer-friendly payment page that includes a QR code: apply as a merchant and read the documentation.
