Method.evm.charge

Choose a signing account

import { privateKeyToAccount } from 'viem/accounts'

export const account = privateKeyToAccount(process.env.PRIVATE_KEY as `0x${string}`)

Creates an EVM charge payment method for client-side EIP-3009 authorization signing.

Usage

The client signs native MPP EVM charge Challenges, route-bound x402 exact Challenges from mppx servers, and standard x402 v2 EIP-3009 Challenges without the optional mppx extension, including Challenges from official Coinbase x402 resource servers.

For x402, the client requires resource information and EIP-3009 token name and version metadata. It enforces the configured network, currency, and amount policies before signing, skips unsupported or rejected offers, and selects a later compatible offer when available.

Advanced options

Defer signer selection

Omit account when you need to inspect or approve the selected Challenge before choosing a signer. Pass the account to createCredential() after preparePayment() returns.

import { Mppx, evm } from 'mppx/client'
import type { Account } from 'viem'
 
declare const account: Account
declare const response: Response
 
const mppx = Mppx.create({
  methods: [
    evm.charge({
      currencies: [evm.assets.base.USDC],
      maxAmount: '1.00',
    }),
  ],
  polyfill: false,
})
 
const payment = await mppx.preparePayment(response)
const credential = await payment.createCredential({ account })

The request-local account overrides a constructor-level account. If neither location supplies a typed-data signer, Credential creation fails without signing or settling anything.

Return type

import type { Method } from 'mppx'
 
type ReturnType = Method.Client

Parameters

account (optional)

• Type: Account

Account that signs EVM charge Credentials. Omit it to choose an account through Credential context after payment preparation.

assets (optional)

• Type: readonly (Address | KnownAsset)[]

Legacy alias for currencies.

authorization (optional)

• Type: { name: string; version: string }

EIP-3009 token domain metadata for custom currencies. Known assets infer this value.

currencies (optional)

• Type: readonly (Address | KnownAsset)[]

Allowlist of EVM currencies the client accepts. Use known assets when possible so mppx can infer chain, decimals, and transfer metadata.

import { evm } from 'mppx/client'
import { privateKeyToAccount } from 'viem/accounts'
 
const method = evm.charge({
  account: privateKeyToAccount(
    '0x0123456789012345678901234567890123456789012345678901234567890123',
  ),
  currencies: [evm.assets.baseSepolia.USDC], 
})

decimals (optional)

• Type: number

Token decimal places used to parse maxAmount when currency metadata doesn't provide decimals.

maxAmount (optional)

• Type: string

Maximum display-unit amount the client pays.

maxAtomicAmount (optional)

• Type: string

Maximum atomic-unit amount the client pays.

networks (optional)

• Type: readonly number[]

Allowlist of EVM chain IDs the client accepts.