Add x402 Payments to Your Agent

Use this page if your self-hosted agent calls x402-protected routes and needs to handle payment alongside the agentlink identity header.

For the x402 payment protocol itself, see x402.org.

Install

pnpm add @x402/core @x402/evm

Wire x402 payment through fetchImpl

import { toClientEvmSigner } from '@x402/evm'
import { x402HTTPClient } from '@x402/core/http'
import { createEvmClient } from '@x402/evm/client'
import { createAgentLinkClient } from '@techdigger/humanode-agentlink'

const paymentClient = new x402HTTPClient(
	createEvmClient({
		signer: toClientEvmSigner(paymentAccount),
	})
)

const { fetch: agentlinkFetch } = createAgentLinkClient({
	network: 'base-sepolia',
	address: '0xYourAgentAddress',
	sign: async message => agentIdentitySigner.signMessage(message),
	fetchImpl: async (input, init) => {
		const request = input instanceof Request ? input : new Request(input, init)
		const first = await fetch(request)
		if (first.status !== 402) return first

		const paymentRequired = paymentClient.getPaymentRequiredResponse(name => first.headers.get(name))
		const paymentPayload = await paymentClient.createPaymentPayload(paymentRequired)
		const retryHeaders = new Headers(request.headers)

		for (const [name, value] of Object.entries(paymentClient.encodePaymentSignatureHeader(paymentPayload))) {
			retryHeaders.set(name, value)
		}

		return fetch(new Request(request, { headers: retryHeaders }))
	},
})

const response = await agentlinkFetch('https://api.example.com/data')

Use the same agent wallet for both the agentlink identity signer and the x402 payment account.

Next steps

• Back to the full operator setup → Self-Hosted Agent Operators
• Calling the two-for-one service → Two-for-One Service
• x402 protocol reference → x402.org