> For the complete documentation index, see [llms.txt](/llms.txt).

# x402 API reference

The following API methods are related to x402 to create payments using [delegation](/smart-accounts-kit/development/reference/glossary#delegation)**Delegation** The ability for a MetaMask smart account to authorize another account to perform specific executions on its behalf..

## `createx402DelegationProvider`[​](#createx402delegationprovider "Direct link to createx402delegationprovider")

Creates a delegation provider function too be used with `x402Erc7710Client`.

The provider resolves creates an [open delegation](/smart-accounts-kit/development/reference/glossary#open-delegation)**Open delegation** A delegation that leaves the delegate unspecified, allowing any account to redeem it., signs it, and returns an ABI-encoded delegation chain as a hex string. The provider internally appends redeemer, payee, and expiry [caveats](/smart-accounts-kit/development/reference/glossary#caveat)**Caveat** A restriction attached to a delegation that limits how delegated authority can be used. when the existing caveats, or the [root delegation](/smart-accounts-kit/development/reference/glossary#root-delegation)**Root delegation** The first delegation in a chain, where an account delegates its own authority directly. doesn't have it.

### Parameters[​](#parameters "Direct link to Parameters")

| Name                    | Type                                                                                                                                                            | Required | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| ----------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| account                 | [MaybeDeferred](/smart-accounts-kit/reference/types/#maybedeferred)<Account>                                                                                    | Yes      | The Viem Account that signs the [delegation](/smart-accounts-kit/development/reference/glossary#delegation)**Delegation** The ability for a MetaMask smart account to authorize another account to perform specific executions on its behalf..                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| environment             | [MaybeDeferred](/smart-accounts-kit/reference/types/#maybedeferred)<[SmartAccountsEnvironment](/smart-accounts-kit/reference/types/#smartaccountsenvironment)\> | No       | Environment to resolve the smart contracts for the current chain. If omitted, resolved automatically from the chain ID in the payment requirements.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| from                    | [MaybeDeferred](/smart-accounts-kit/reference/types/#maybedeferred)<Hex>                                                                                        | No       | The address that is granting the [delegation](/smart-accounts-kit/development/reference/glossary#delegation)**Delegation** The ability for a MetaMask smart account to authorize another account to perform specific executions on its behalf.. The default is account.                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| salt                    | [MaybeDeferred](/smart-accounts-kit/reference/types/#maybedeferred)<Hex>                                                                                        | No       | The salt for generating the delegation hash. The default is a random 32-byte value.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| caveats                 | [MaybeDeferred](/smart-accounts-kit/reference/types/#maybedeferred)<Caveats>                                                                                    | No       | [Caveats](/smart-accounts-kit/development/reference/glossary#caveat)**Caveat** A restriction attached to a delegation that limits how delegated authority can be used. that further refine the authority granted by the [delegation](/smart-accounts-kit/development/reference/glossary#delegation)**Delegation** The ability for a MetaMask smart account to authorize another account to perform specific executions on its behalf.. [redeemer](/smart-accounts-kit/reference/delegation/caveats/#redeemer), [allowedTargets](/smart-accounts-kit/reference/delegation/caveats/#allowedtargets), and [timestamp](/smart-accounts-kit/reference/delegation/caveats/#timestamp) caveats are auto-appended if not already present. |
| parentPermissionContext | [MaybeDeferred](/smart-accounts-kit/reference/types/#maybedeferred)<PermissionContext>                                                                          | No       | Parent chain as Hex or as decoded [Delegation](/smart-accounts-kit/reference/types/#delegation) values (leaf first). Use this when creating a [redelegation](/smart-accounts-kit/development/reference/glossary#redelegation)**Redelegation** A delegation that passes on authority granted by a previous delegation..                                                                                                                                                                                                                                                                                                                                                                                                            |
| expirySeconds           | [MaybeDeferred](/smart-accounts-kit/reference/types/#maybedeferred)<number>                                                                                     | No       | Relative expiry in seconds. Adds a timestamp caveat if no tighter constraint exists.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| redeemers               | [MaybeDeferred](/smart-accounts-kit/reference/types/#maybedeferred)<[RedeemersConfig](/smart-accounts-kit/reference/types/#redeemersconfig)\>                   | No       | Constrains the addresses that are allowed to redeem the [delegation](/smart-accounts-kit/development/reference/glossary#delegation)**Delegation** The ability for a MetaMask smart account to authorize another account to perform specific executions on its behalf.. Use this to restrict redemption to specific facilitators.                                                                                                                                                                                                                                                                                                                                                                                                  |

### Example[​](#example "Direct link to Example")

- Delegation
- Redelegation

```
import { privateKeyToAccount } from 'viem/accounts'
import { createx402DelegationProvider } from '@metamask/smart-accounts-kit/experimental'
import { x402Erc7710Client } from '@metamask/x402'

const account = privateKeyToAccount(privateKey)

const erc7710Client = new x402Erc7710Client({
  delegationProvider: createx402DelegationProvider({
    account,
  }),
})

```

```
import { createx402DelegationProvider } from '@metamask/smart-accounts-kit/experimental'

const parentPermissionContext = '0x...' // Previously stored/issued permission context.

const delegationProvider = createx402DelegationProvider({
  account,
  parentPermissionContext,
})

```

## `parseEip155ChainId`[​](#parseeip155chainid "Direct link to parseeip155chainid")

Parses an [EIP-155 CAIP](https://namespaces.chainagnostic.org/eip155/caip2) network identifier into a numeric chain ID.

### Parameters[​](#parameters-1 "Direct link to Parameters")

| Name    | Type   | Required | Description                                             |
| ------- | ------ | -------- | ------------------------------------------------------- |
| network | string | Yes      | EIP-155 CAIP network identifier. For example, eip155:1. |

### Example[​](#example-1 "Direct link to Example")

```
import { parseEip155ChainId } from '@metamask/smart-accounts-kit/experimental'

// Returns 137
const chainId = parseEip155ChainId('eip155:137')

```