Network Support

x402 supports multiple blockchain networks for payment processing. This page covers what the x402 reference SDKs support, what the CDP facilitator is configured for, and where to find other facilitators.

Network Identifiers (CAIP-2)

x402 v2 uses CAIP-2 (Chain Agnostic Improvement Proposal) format for network identifiers. This provides a standardized way to identify blockchain networks across the ecosystem.

CAIP-2 Format

The format is: namespace:reference

• EVM Networks: eip155:{chainId} where chainId is the EVM chain ID
• Solana Networks: solana:{genesisHash} where genesisHash is a truncated genesis hash

Examples

// EVM networks
network: "eip155:8453"      // Base mainnet (chain ID 8453)
network: "eip155:84532"     // Base Sepolia (chain ID 84532)
network: "eip155:137"       // Polygon mainnet (chain ID 137)
network: "eip155:42161"     // Arbitrum One mainnet (chain ID 42161)
network: "eip155:480"       // World mainnet (chain ID 480)
network: "eip155:1"         // Ethereum mainnet (chain ID 1)

// Solana networks
network: "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp"  // Solana mainnet
network: "solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1"  // Solana devnet

Reference SDK Support

The x402 reference SDKs are designed to be flexible and extensible:

EVM Support (@x402/evm)

The @x402/evm package supports any EVM-compatible chain you configure and all ERC-20 tokens via two transfer methods:

• EIP-3009 (Transfer With Authorization): For tokens that natively implement EIP-3009, such as USDC and EURC. The buyer signs an off-chain authorization and the facilitator submits the transfer — no on-chain approval needed.
• Permit2: For any ERC-20 token, using Permit2 as a universal token approval mechanism. The buyer signs a PermitWitnessTransferFrom message and the facilitator executes the transfer.

This includes:

• Any Ethereum L1 or L2
• Any EVM-compatible chain with a valid chain ID
• Any ERC-20 token (via Permit2) or EIP-3009 compliant token (USDC, EURC, etc.)

Permit2 Approval

Permit2 requires the buyer to have an active approval from the payment token to the Permit2 contract. x402 supports two gas sponsorship extensions that handle this approval automatically:

• EIP-2612 gas sponsoring: For tokens that implement EIP-2612 (permit), the facilitator can sponsor the Permit2 approval on-chain using a signed off-chain permit message — no gas required from the buyer.
• ERC-20 gas sponsoring: For generic ERC-20 tokens without EIP-2612 support, the facilitator can sponsor the Permit2 approval transaction on the buyer’s behalf.

Without a gas sponsorship extension, the buyer must perform a one-time manual approval of the payment token to the Permit2 contract before making their first payment.

EIP-3009 and Permit2 (including gas sponsorship extensions) are supported in the official TypeScript (@x402/evm), Go, and Python SDKs.

Solana Support (@x402/svm)

The @x402/svm package supports any Solana cluster with:

• SPL Token Program tokens
• Token2022 program tokens

Other SDKs

Community and third-party SDKs may expand support to other protocol families or chains beyond what the reference SDKs currently support. Check the x402 ecosystem for additional implementations.

CDP Facilitator Support

The CDP (Coinbase Developer Platform) facilitator is our recommended choice for both testnet and mainnet. It supports the following networks and schemes:

Network	CAIP-2 Identifier	v1 Support	v2 Support	Scheme	Pricing
Base	eip155:8453	✅	✅	exact, upto	Free tier*
Base Sepolia	eip155:84532	✅	✅	exact, upto	Free tier*
Polygon	eip155:137	✅	✅	exact, upto	Free tier*
Arbitrum	eip155:42161	✅	✅	exact, upto	Free tier*
World	eip155:480	✅	✅	exact, upto	Free tier*
World Sepolia	eip155:4801	✅	✅	exact, upto	Free tier*
Solana	solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp	✅	✅	exact	Free tier*
Solana Devnet	solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1	✅	✅	exact	Free tier*

*1,000 transactions free per month, then $0.001/transaction. Gas is paid on-chain separately. See Facilitator Pricing for details.

CDP Facilitator Endpoints:

• Mainnet: https://api.cdp.coinbase.com/platform/v2/x402
  • Requires CDP API keys
  • Supports: Base, Polygon, Arbitrum, World, Solana

x402.org Testnet Facilitator

For testnet-only use without CDP signup, the x402.org facilitator is available:

Network	CAIP-2 Identifier	v1 Support	v2 Support	Scheme
Base Sepolia	eip155:84532	✅	✅	exact, upto
Solana Devnet	solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1	✅	✅	exact

Endpoint: https://x402.org/facilitator

• No API key required
• For testnet use only

Other Facilitators

The x402 protocol is permissionless, so anyone can run a facilitator. The ecosystem includes several community and third-party facilitators that support additional networks, tokens, and features.

For a complete and up-to-date list of facilitators, visit the x402 Ecosystem.

Chain ID Reference

Quick reference for common EVM chain IDs:

Chain ID	Network	CAIP-2 Format
1	Ethereum Mainnet	eip155:1
10	Optimism	eip155:10
137	Polygon	eip155:137
8453	Base	eip155:8453
84532	Base Sepolia	eip155:84532
42161	Arbitrum One	eip155:42161
480	World	eip155:480
4801	World Sepolia	eip155:4801
43114	Avalanche C-Chain	eip155:43114
43113	Avalanche Fuji	eip155:43113

Token Support

EVM Networks

On EVM networks, x402 supports all ERC-20 tokens via two transfer methods:

• EIP-3009 tokens (e.g., USDC, EURC): Use EIP-3009 (Transfer With Authorization) for fully gasless transfers where the buyer signs an off-chain message and the facilitator submits the transaction. No on-chain approval step is needed.
• Generic ERC-20 tokens: Use Permit2 for transfers. The buyer must have an approval to the Permit2 contract, which can be handled via gas sponsorship extensions (EIP-2612 or ERC-20 gas sponsoring) or a one-time manual approval.

Common EIP-3009 Tokens:

Token	Base	Base Sepolia	Polygon	Arbitrum	World
USDC	0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913	0x036CbD53842c5426634e7929541eC2318f3dCF7e	0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359	0xaf88d065e77c8cC2239327C5EDb3A432268e5831	0x79A02482A880bCE3F13e09Da970dC34db4CD24d1

Any ERC-20 token can be used with x402 via Permit2. EIP-3009 compliant tokens like USDC provide the smoothest experience since they require no on-chain approval. The token addresses above are the most commonly used with the CDP facilitator.

Solana Networks (SPL / Token2022)

On Solana, x402 supports SPL Token Program tokens for v1 and v2, and Token2022 program tokens for v2 only.

Common Tokens:

Token	Mainnet	Devnet
USDC	EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v	(faucet available)

Price Formatting

x402 supports multiple price formats for convenience:

// Dollar string format (recommended for readability)
price: "$0.001"    // 0.001 USDC
price: "$1.00"     // 1 USDC
price: "$0.50"     // 0.50 USDC

// Atomic units (for precision)
amount: "1000"     // 0.001 USDC (6 decimals)
amount: "1000000"  // 1 USDC (6 decimals)

Usage Examples

Server-Side Configuration

Node.js

import { paymentMiddleware, x402ResourceServer } from "@x402/express";
import { ExactEvmScheme } from "@x402/evm/exact/server";
import { HTTPFacilitatorClient } from "@x402/core/server";

const facilitatorClient = new HTTPFacilitatorClient({
  url: "https://x402.org/facilitator",
});

// Register scheme for Base Sepolia
const server = new x402ResourceServer(facilitatorClient)
  .register("eip155:84532", new ExactEvmScheme());

app.use(
  paymentMiddleware(
    {
      "GET /api": {
        accepts: [
          {
            scheme: "exact",
            price: "$0.001",
            network: "eip155:84532", // Base Sepolia
            payTo: "0xYourAddress",
          },
        ],
        description: "API endpoint",
      },
    },
    server,
  ),
);

Go

import (
    x402 "github.com/x402-foundation/x402/go"
    x402http "github.com/x402-foundation/x402/go/http"
    evm "github.com/x402-foundation/x402/go/mechanisms/evm/exact/server"
)

network := x402.Network("eip155:84532") // Base Sepolia

r.Use(ginmw.X402Payment(ginmw.Config{
    Routes: x402http.RoutesConfig{
        "GET /api": {
            Scheme:  "exact",
            PayTo:   payTo,
            Price:   "$0.001",
            Network: network,
        },
    },
    Facilitator: facilitatorClient,
    Schemes: []ginmw.SchemeConfig{
        {Network: network, Server: evm.NewExactEvmScheme()},
    },
}))

Using a Custom Network

Since @x402/evm supports any EVM chain, you can configure networks not listed above:

// Example: Using Ethereum mainnet with a custom facilitator
const facilitatorClient = new HTTPFacilitatorClient({
  url: "https://example.facilitator.com",
});

const server = new x402ResourceServer(facilitatorClient)
  .register("eip155:1", new ExactEvmScheme()); // Ethereum mainnet

app.use(
  paymentMiddleware(
    {
      "GET /api": {
        accepts: [
          {
            scheme: "exact",
            price: "$0.001",
            network: "eip155:1",
            payTo: "0xYourAddress",
            asset: "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48", // USDC on Ethereum
          },
        ],
        description: "API endpoint",
      },
    },
    server,
  ),
);

Multi-Network Support

Support multiple networks on the same endpoint:

{
  "GET /api": {
    accepts: [
      {
        scheme: "exact",
        price: "$0.001",
        network: "eip155:8453",  // Base mainnet
        payTo: "0xYourEvmAddress",
      },
      {
        scheme: "exact",
        price: "$0.001",
        network: "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",  // Solana mainnet
        payTo: "YourSolanaAddress",
      },
    ],
    description: "Multi-network endpoint",
  },
}

Running Your Own Facilitator

If you need to support networks or tokens not available through existing facilitators, you can run your own:

1. Use the reference implementation: The x402 GitHub repository contains facilitator code
2. Use a community implementation: Check the x402 Ecosystem for self-hostable options

Next Steps

• Quickstart for Sellers - Start accepting payments
• Quickstart for Buyers - Start making payments
• Core Concepts: Facilitator - Learn about facilitators
• x402 Ecosystem - Explore facilitators and tools