Technical Reference

Blockchain in Payments

Working principles, network types, consensus mechanisms, DeFi protocols, stablecoins, and CBDCs — a technical guide to blockchain technology and its integration with modern payment infrastructure.

3–5 sXRPL / Stellar finality

$150B+stablecoin supply

130+CBDC projects globally

1M TPSLightning theoretical max

Tether (USDT) Overview

Tether (USDT) is the largest stablecoin by market capitalisation — roughly $190 billion outstanding — issued by Tether Limited and designed to track the US dollar 1:1. Crucially, USDT is not its own blockchain: it is a token contract deployed across ~10 host chains, so a "USDT payment" is a token transfer on whichever chain you choose, settled in that chain's blocks and paid for in that chain's native gas coin.

Where USDT lives

Chain	Token standard	Share of supply	Typical use
Tron	TRC-20	~45%	Cross-border transfers & remittances (near-zero fees)
Ethereum	ERC-20	~40%	DeFi collateral, institutional settlement, CEX float
Solana	SPL	Growing	Fast, low-cost retail & payments
Others	Avalanche, Polygon, TON, Liquid, Near…	Small	Ecosystem-specific liquidity
Legacy	Omni (on Bitcoin)	Deprecated	Original 2014 issuance, being wound down

Reserves & backing

Tether publishes quarterly attestations by BDO Italia (an attestation is a point-in-time review, not a full financial audit). Reported reserve composition:

Asset	Approx. share
US Treasury bills (direct + indirect)	~80%
Overnight repo & cash equivalents	Mid single digits
Gold	~$8 B
Bitcoin	~$7 B
Secured loans & other investments	Remainder

Tether's Treasury exposure (~$100B+) would rank it among the largest sovereign holders of US debt. Reserve transparency has historically been questioned, and Tether has not completed a full audit.

Integrating USDT payments

A USDT transfer is an ordinary token transfer on the host chain. You move USDT but pay the network fee in that chain's native coin — ETH on Ethereum, TRX on Tron, SOL on Solana. USDT uses 6 decimals on Ethereum and Tron (so 1 USDT = 1000000 base units), unlike most 18-decimal ERC-20s.

Property	Ethereum	Tron	Solana
Standard	ERC-20	TRC-20	SPL
Decimals	6	6	6
Gas paid in	ETH	TRX (or energy)	SOL
Typical fee	$1–$10	~$1 or free	<$0.001
Finality	~12 min	~1 min	~0.4s

Canonical contract / mint addresses

Ethereum (ERC-20)

0xdAC17F958D2ee523a2206206994597C13D831ec7

Tron (TRC-20)

TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t

Solana (SPL mint)

Es9vMFrzaCERmJfrF4H2FYD4KCoNkY11McCe8BenwNYB

Merchant settlement flow

1. Generate request

Merchant shows a chain-specific address (or payment URI / QR) and the USDT amount, picking a chain that suits fee and speed needs.

2. Customer transfers

Wallet calls the token contract's transfer(to, amount) with the amount in 6-decimal base units, paying gas in the native coin.

3. Merchant confirms

Backend watches the contract's Transfer event for the expected amount & reference, then releases goods after the chain's finality window.

Regulatory & compliance notes

EU / MiCA: Tether has not obtained MiCA e-money-token authorisation, and major EU exchanges have delisted USDT spot pairs for EEA users since 2025. US / GENIUS Act (2025): a federal payment-stablecoin framework exists; Tether has not signalled it will register under it. USDT contracts include an issuer freeze/blacklist function used for law-enforcement requests. Always confirm USDT's legal availability in your users' jurisdictions before integrating.