Accepting USDT on Tron without a payment processor: what we check before crediting
When we added crypto top-ups to VerifDoc, many customers in South Asia asked for one thing: USDT on Tron (TRC-20) . It's what they hold on exchanges, and network fees are a few cents. Here's how we accept it without a payment processor, and the checks that stop us from crediting money that never arrived. The shape of it We keep a small pool of Tron wallets. A customer starts a deposit, gets a…
VerifDoc added support for crypto top-ups, with customers in South Asia requesting USDT on Tron (TRC-20). To accept USDT without a payment processor, the company maintains a small pool of Tron wallets. When a customer initiates a deposit, they receive a wallet and an amount, and then send USDT. A scanner looks for TRC-20 transfers into the wallet and confirms each candidate on a solidity node before crediting.
The process includes several checks to ensure the received USDT is genuine. Firstly, the token must be verified as USDT by checking its contract address (TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t) against the list of candidates and the receipt. Secondly, the transaction must be confirmed on the solidity node to ensure it has been included in a confirmed block.
Thirdly, the Tron addresses must be validated properly, as they are base58check with a 0x41 prefix, 20 bytes, and a 4-byte double-SHA256 checksum. Lastly, the system ensures that each transfer is credited only once by using a unique key on the network along with transaction ID and log index in the database.
The scanner keeps a cursor per wallet, re-reading a small overlap window each run to ensure transfers missed between runs are not missed. Only one open deposit per wallet is allowed at a time. The entire flow was tested locally against a real mainnet transfer, and the second pass of testing confirmed that no double-credit occurred.
Once the system was up and running, the first real customer deposit arrived the day after it was implemented. For those accepting stablecoins like USDT or USDC, it is crucial to match contracts rather than symbols, rely on receipts instead of indexes, and ensure the credit process is idempotent.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
