@okxweb3/x402-evm

EVM implementation of the x402 payment protocol for X Layer. Supports EIP-3009 transferWithAuthorization and aggregated deferred payment schemes.

Installation

npm install @okxweb3/x402-evm

Supported Chain

| Chain | CAIP-2 ID | Default Stablecoin | Transfer Method | | --- | --- | --- | --- | | X Layer | eip155:196 | USDT0 | EIP-3009 |

Supported Schemes

• exact — Standard payment. The exact amount is transferred on-chain via EIP-3009 transferWithAuthorization.
• aggr_deferred — Aggregated deferred payment using session keys. The facilitator batches multiple payments on-chain for high-throughput scenarios.

Exports

Main entry (@okxweb3/x402-evm)

• ExactEvmScheme — Client-side Exact scheme (EIP-3009)
• AggrDeferredEvmClientScheme / AggrDeferredEvmServerScheme — Aggregated deferred payment scheme
• toClientEvmSigner(account) / toFacilitatorEvmSigner(wallet) — Convert viem objects to x402 signers
• Type guards: isEIP3009Payload

Subpath exports

| Path | Description | | --- | --- | | @okxweb3/x402-evm/exact/server | Server-side Exact scheme (builds payment requirements) | | @okxweb3/x402-evm/exact/facilitator | Facilitator Exact scheme (verifies & settles payments) | | @okxweb3/x402-evm/deferred/client | Deferred payment client scheme | | @okxweb3/x402-evm/deferred/server | Deferred payment server scheme |

Usage

Client-side (signing payments)

import { x402Client } from "@okxweb3/x402-core/client";
import { ExactEvmScheme, toClientEvmSigner } from "@okxweb3/x402-evm";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount("0x...");
const signer = toClientEvmSigner(account);

const client = new x402Client()
  .register("eip155:196", new ExactEvmScheme(signer));

Server-side (building payment requirements)

import { ExactEvmScheme } from "@okxweb3/x402-evm/exact/server";

const evmServer = new ExactEvmScheme();

Facilitator (verifying & settling payments)

import { ExactEvmScheme } from "@okxweb3/x402-evm/exact/facilitator";
import { toFacilitatorEvmSigner } from "@okxweb3/x402-evm";

const facilitator = new ExactEvmScheme(toFacilitatorEvmSigner(walletClient));

Asset Transfer Method

Tokens on X Layer use EIP-3009 (transferWithAuthorization), which provides gasless, single-signature token transfers. The default stablecoin is USDT0.

Related Packages

• @okxweb3/x402-core — Core protocol types and client