@t402/wdk-gasless

Gasless USDT0 payments with Tether WDK and ERC-4337 Account Abstraction.

Features

- Gasless Payments: Send USDT0/USDC without paying gas fees
- ERC-4337 Integration: Uses Safe smart accounts with Account Abstraction
- Batch Payments: Execute multiple transfers in a single transaction
- Multi-Chain Support: Ethereum, Arbitrum, Base, Optimism, Ink, Berachain, Unichain
- Paymaster Sponsorship: Optional gas sponsorship via paymasters

Installation

``bash
npm install @t402/wdk-gasless


or


pnpm add @t402/wdk-gasless
`

$3

`bash
npm install @tetherto/wdk @tetherto/wdk-wallet-evm
`

Quick Start

`typescript
import { createWdkGaslessClient } from '@t402/wdk-gasless'
import { createPublicClient, http } from 'viem'
import { arbitrum } from 'viem/chains'

// Create a public client
const publicClient = createPublicClient({
chain: arbitrum,
transport: http(),
})

// Create the gasless client
const client = await createWdkGaslessClient({
wdkAccount: myWdkAccount, // From @tetherto/wdk
publicClient,
chainId: 42161, // Arbitrum
bundler: {
bundlerUrl: 'https://api.pimlico.io/v2/arbitrum/rpc?apikey=YOUR_KEY',
chainId: 42161,
},
paymaster: {
address: '0x...',
url: 'https://api.pimlico.io/v2/arbitrum/rpc?apikey=YOUR_KEY',
type: 'sponsoring',
},
})

// Execute a gasless payment
const result = await client.pay({
to: '0xRecipientAddress...',
amount: 1000000n, // 1 USDT0 (6 decimals)
})

// Wait for confirmation
const receipt = await result.wait()
console.log('Payment confirmed:', receipt.txHash)
`

API Reference

$3

Creates a new gasless payment client.

`typescript
interface CreateWdkGaslessClientConfig {
wdkAccount: WdkAccount // WDK account from @tetherto/wdk
publicClient: PublicClient // Viem public client
chainId: number // Chain ID
bundler: BundlerConfig // Bundler configuration
paymaster?: PaymasterConfig // Optional paymaster for gas sponsorship
saltNonce?: bigint // Salt for address generation (default: 0n)
}
`

$3

#### pay(params): Promise

Execute a single gasless payment.

`typescript
interface GaslessPaymentParams {
to: Address // Recipient address
amount: bigint // Amount in token decimals
token?: 'USDT0' | 'USDC' | Address // Token (default: 'USDT0')
}

interface GaslessPaymentResult {
userOpHash: Hex // UserOperation hash
sender: Address // Smart account address
sponsored: boolean // Whether gas was sponsored
wait(): Promise
}
`

#### payBatch(params): Promise

Execute multiple payments in a single transaction.

`typescript
interface BatchPaymentParams {
payments: Array<{
to: Address
amount: bigint
token?: 'USDT0' | 'USDC' | Address
}>
}
`

#### canSponsor(params): Promise

Check if a payment can be gas-sponsored.

`typescript
interface SponsorshipInfo {
canSponsor: boolean
reason?: string
estimatedGasCost?: bigint
}
`

#### getBalance(token?): Promise

Get the token balance of the smart account.

#### getFormattedBalance(token?, decimals?): Promise

Get the formatted token balance (human-readable).

#### getAccountAddress(): Promise

Get the smart account address.

#### isAccountDeployed(): Promise

Check if the smart account is deployed on-chain.

Supported Chains

| Chain | Chain ID | USDT0 | USDC |
| --------- | -------- | ----- | ---- |
| Ethereum | 1 | ✅ | ✅ |
| Arbitrum | 42161 | ✅ | ✅ |
| Base | 8453 | ✅ | ✅ |
| Optimism | 10 | ✅ | ✅ |
| Ink | 57073 | ✅ | - |
| Berachain | 80094 | ✅ | - |
| Unichain | 130 | ✅ | - |

Constants

`typescript
import {
USDT0_ADDRESSES,
USDC_ADDRESSES,
CHAIN_IDS,
getTokenAddress,
getChainName,
} from '@t402/wdk-gasless'

// Get USDT0 address on Arbitrum
const usdt0 = USDT0_ADDRESSES.arbitrum
// '0xFd086bC7CD5C481DCC9C85ebE478A1C0b69FCbb9'

// Get chain name from ID
const chainName = getChainName(42161)
// 'arbitrum'
`

Smart Account Architecture

This package uses Safe smart accounts with ERC-4337 support:

- Safe Singleton: 0x29fcB43b46531BcA003ddC8FCB67FFE91900C762
- Safe 4337 Module: 0xa581c4A4DB7175302464fF3C06380BC3270b4037 (v0.3.0)
- Proxy Factory: 0x4e1DCf7AD4e460CfD30791CCC4F9c8a4f820ec67
- EntryPoint: 0x0000000071727De22E5E9d8BAf0edAc6f37da032 (v0.7)

Examples

$3

`typescript
const result = await client.payBatch({
payments: [
{ to: '0xAlice...', amount: 500000n }, // 0.5 USDT0
{ to: '0xBob...', amount: 300000n }, // 0.3 USDT0
{ to: '0xCharlie...', amount: 200000n }, // 0.2 USDT0
],
})

const receipt = await result.wait()
console.log(Batch payment in tx: ${receipt.txHash})
`

$3

`typescript
const sponsorship = await client.canSponsor({
to: '0xRecipient...',
amount: 1000000n,
})

if (sponsorship.canSponsor) {
console.log('Payment will be free!')
} else {
console.log(Gas cost: ${sponsorship.estimatedGasCost} wei)
}
`

$3

`typescript
const result = await client.pay({
to: '0xRecipient...',
amount: 1000000n,
token: 'USDC',
})
`

Related Packages

- @t402/core - Core protocol types and client
- @t402/wdk - Tether WDK integration
- @t402/wdk-bridge - Cross-chain LayerZero bridging
- @t402/wdk-multisig - Safe multi-sig wallets
- @t402/evm` - EVM mechanism implementation

License

Apache-2.0