JAVASCRIPT SDKv0.3.20

Use HTTP payment challenges.

An advanced Playmos x402-shaped envelope over the transfer settlement core.

Choose this after the basic payment flow#

This service product is server-only: use your sk_test_ key, Base Sepolia and an enabled x402 settlement capability. Public pk_ keys and live/mainnet x402 are refused. Use IAP pay → verify for game purchases. This route is for HTTP services that deliberately integrate Playmos challenges. It is not a claim of interoperability with every stock x402 client or facilitator.

Local shape versus service challenge#

createPaymentRequirement and createX402Challenge build a local 402 response with a PAYMENT-REQUIRED header. They do not register a settleable challenge on the service. Use client.x402.challenge and fulfill, or client.x402.pay which performs that sequence.

Keep units explicit#

The SDK takes amount: '0.10'. The envelope’s maxAmountRequired is atomic USDC: '100000'. Network is key-selected Base Sepolia for test keys. Decode and validate challenge inputs; server-issued terms and fees are authoritative, not edits from the client.

Inspect the settlement result#

The result can remain pending or settling; only settled is terminal success, and failed is failure and the actual transaction hash. A locally constructed 402 body is not evidence that money moved. Persist a stable requirement ID before creating the challenge and retain the returned requirement to reconcile interrupted fulfillment with the same terms. A new ID creates a new operation.

Keep buildingYour first payment

import { Playmos } from '@playmos/sdk';
import { createPaymentRequirement, createX402Challenge } from '@playmos/sdk';
export function localHttpChallenge(payTo: `0x${string}`) {
const requirement = createPaymentRequirement({
payTo, amount: '0.10', network: 'base-sepolia',
});
return createX402Challenge(requirement, { feeBps: 0 });
// Response shape only: 402, PAYMENT-REQUIRED, atomic maxAmountRequired.
}
export async function payHttpRequirement(
client: Playmos, payTo: `0x${string}`, savedRequirementId: string,
) {
// The SDK mints a service challenge, then fulfills it on Playmos rails.
return client.x402.pay({ payTo, amount: '0.10', feeBps: 0, id: savedRequirementId });
// Inspect settled / settling / failed and the actual transaction hash.
}