> ## Documentation Index
> Fetch the complete documentation index at: https://www.agentcommercekit.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ACK-Pay Payments Demo

> Interactive guide demonstrating ACK-Pay payment flows.

## Overview

**ACK-Pay** is a protocol built on W3C Standards designed to facilitate secure, verifiable, and interoperable financial transactions among autonomous agents, services, and human participants.

This interactive command-line demo illustrates the [**Server-Initiated payment flow**](/ack-pay/server-initiated-sequence), including:

* A **Client Agent** attempting to access a protected resource.
* A **Server Agent** issuing a Payment Request.
* The Client making a payment.
* A **Receipt Service** verifying the payment and issuing a receipt (in the form of a Verifiable Credential).
* Client using the receipt to access the protected resource.

## Demo Video

<iframe width="560" height="315" src="https://www.youtube.com/embed/49VaG1-u1i0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen />

## Getting Started

Before running this demo, follow the [Quickstart Guide](./quickstart) at the repository root.

## Running the Demo

Run from the repository root:

```sh theme={null}
pnpm run demo:payments
```

Alternatively, run from within the demo directory (`./demos/payments`):

```sh theme={null}
pnpm run demo
```

## ACK-Pay Demo Components

* **Client**: The interactive agent requesting access to resources and making payments.
* **Server**: An HTTP server protecting resources and issuing payment requests.
* **Receipt Service**: HTTP service validating payments and issuing verifiable receipts (VCs).
* **Payment Service** (illustrated in optional paths): Handles credit card payments, currency conversion, compliance checks (KYC/AML), and complex payment routing.

## Demo Walkthrough

The interactive CLI guides you through these steps:

<Steps>
  <Step title="Resource Request">
    Client requests access to a protected resource. Server responds with an HTTP `402 Payment Required` status containing a `PaymentRequest`.
  </Step>

  <Step title="Making Payment">
    Client performs an on-chain stablecoin (USDC) payment to the Server's wallet
    on Base Sepolia testnet or Solana devnet. Alternatively, a credit card payment
    can be handled via a Payment Service.
  </Step>

  <Step title="Receipt Request">
    After payment completion, Client requests a receipt (VC) from the Receipt
    Service by providing proof of payment.
  </Step>

  <Step title="Receipt Verification">
    Receipt Service verifies provided transaction details and issues a Receipt
    Credential.
  </Step>

  <Step title="Accessing the Resource">
    Client retries accessing the resource, presenting the receipt to the Server.
    Server verifies receipt authenticity and grants resource access.
  </Step>
</Steps>

## Further Exploration

Explore comprehensive ACK-Pay functionalities and integrations in real-world applications involving diverse payment methods and Payment Service integrations:

* [View Payments Demo Source Code](https://github.com/agentcommercekit/ack/tree/main/demos/payments)
* [ACK Documentation](https://agentcommercekit.com)
* [ACK-Pay Details](/ack-pay/introduction)