Develop with Atum SDK

1. Install the package

npm install @atumlabs/x402-atum-escrow @x402/core @x402/fetch ethers

2. Register the scheme and wrap fetch

import { ethers } from "ethers";
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerAtumEscrowScheme } from "@atumlabs/x402-atum-escrow/client";

const client = new x402Client();
registerAtumEscrowScheme(client, { signer: new ethers.Wallet(PRIVATE_KEY) });

const fetchWithPayment = wrapFetchWithPayment(fetch, client);

// Call it exactly like fetch — your agent's tool-call code doesn't need to
// branch on whether the resource is x402-gated.
const res = await fetchWithPayment("https://merchant.example/paid");

registerAtumEscrowScheme reads the selected 402 option’s extra.atum (destination, deadlines, settlement vault/proxy/role addresses), builds the Atum payment request, and signs the source-side Permit2 authorization for the settlement vault deposit. Before it signs anything, the client checks the merchant’s terms and refuses the payment with an AtumEscrowTrustError if they fail. See What payers check before signing. Paying through a deployment other than Atum’s production gateways? Pass your own trust to registerAtumEscrowScheme, or every payment is refused.

3. Restrict source networks (optional)

registerAtumEscrowScheme registers under the eip155:* wildcard by default — pass an explicit networks list to restrict which source chains your agent will fund from:

registerAtumEscrowScheme(client, {
  signer: new ethers.Wallet(PRIVATE_KEY),
  networks: ["eip155:8453"], // illustrative CAIP-2 id (Base mainnet) — substitute the source chains you fund from
});

Chain IDs, tokens, and addresses in these snippets are illustrative placeholders. Use Supported networks and Supported assets for the live catalog.

The source token must already have an approve(Permit2) allowance covering the spend, or the settlement vault deposit reverts at settlement. Arranging that is your agent/app’s responsibility — the mechanism assumes it and does not check on-chain. See the Permit2 allowance prerequisite in Agentic sends for a preflight pattern.

4. Build a payment without sending it (optional)

If you’d rather build a payment without immediately sending the request — for example to inspect it, log it, or drive a facilitator’s /verify directly — read the 402 yourself and build the payload from the HTTP client wrapper (x402HTTPClient, which wraps your x402Client): httpClient.createPaymentPayload(paymentRequired), instead of using wrapFetchWithPayment.

Next steps

Topic	Link
Run the demo first	Agentic sends
Merchant-side guide	Accept payments
Facilitator API reference	x402 Facilitator API
Supported chains and tokens	Supported kinds
Agent-initiated payouts (not x402)	Agentic payouts

Start here

Facilitated payments (x402)

Direct payments (MPP)

Develop with Atum SDK

1. Install the package

2. Register the scheme and wrap fetch

3. Restrict source networks (optional)

4. Build a payment without sending it (optional)

Next steps

​1. Install the package

​2. Register the scheme and wrap fetch

​3. Restrict source networks (optional)

​4. Build a payment without sending it (optional)

​Next steps

1. Install the package

2. Register the scheme and wrap fetch

3. Restrict source networks (optional)

4. Build a payment without sending it (optional)

Next steps