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

# Merchant Introduction

> Choose an x402 server integration, configure PayAI facilitation, and prepare payment, discovery and recovery behavior.

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## Charge for an HTTP resource

An x402 resource server advertises payment requirements and uses a facilitator to verify and settle supported payments. Your application still owns resource delivery, pricing, access control and recovery.

If you want to pay for a resource instead, start with the [client guide](/x402/clients/introduction). For a first end-to-end example, use the [quickstart](/x402/quickstart).

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## Choose your server

Use a complete framework guide for installation, environment variables and a runnable example. Use a manual flow when you need to control the payment lifecycle directly.

| Your application uses | Start here |
| - | - |
| Base Mainnet USDC with Express | [Base Mainnet Express](/x402/base-mainnet-express) |
| TypeScript with Express | [Express server](/x402/servers/typescript/express) |
| TypeScript with Hono | [Hono server](/x402/servers/typescript/hono) |
| TypeScript with Next.js | [Next.js server](/x402/servers/typescript/nextjs) |
| Python with FastAPI | [FastAPI server](/x402/servers/python/fastapi) |
| Python with Flask | [Flask server](/x402/servers/python/flask) |
| Go with Gin | [Gin server](/x402/servers/go/gin) |
| A custom TypeScript payment flow | [TypeScript manual flow](/x402/servers/typescript/manual-flow) |
| A custom Python payment flow | [Python manual flow](/x402/servers/python/manual-flow) |
| Metered Solana payments with channels and vouchers | [Batch settlement public preview](/x402/servers/batch-settlement) |
| Metered payments on Base with channels and vouchers | [EVM batch settlement on Base](/x402/servers/evm-batch-settlement) |

Batch settlement has separate SDK, funding, authentication and channel-recovery requirements. Do not apply an exact-payment example to it unchanged.

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## Understand the payment flow

<img src="https://mintcdn.com/payai/2DGsVUJGFkMxMKTt/images/x402-sequence-diagram.svg?fit=max&auto=format&n=2DGsVUJGFkMxMKTt&q=85&s=750a29402143e49980393d116826ef2d" alt="x402 sequence diagram" width="1992" height="1570" data-path="images/x402-sequence-diagram.svg" />

The server challenges an unpaid request, accepts a retry carrying a payment authorization, and verifies the selected terms. Settlement and resource delivery must follow the lifecycle required by your integration. See the [x402 reference](/x402/reference) for wire formats and the [facilitator introduction](/x402/facilitators/introduction) for PayAI's role.

HTTP compatibility alone is not payment compatibility: both ends must support the selected network, token and scheme. Check [supported networks](/x402/supported-networks). Fee sponsorship depends on the payment flow, and end-to-end latency depends on application work, transport and settlement; neither zero network costs nor sub-second settlement is universal.

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## Configure PayAI and prepare production

1. Follow your framework guide's PayAI facilitator configuration. Review the [free allowance and production pricing](/x402/facilitators/pricing); ordinary exact payments can serve mainnet production traffic without an API key until the applicable allowance is exhausted.
2. For paid usage or an assigned lane, keep facilitator credentials on the server. An autonomous agent can [buy credits and receive a key over x402](/x402/facilitators/agent-api-keys) with no portal signup; the paying wallet gets a wallet-owned agent account programmatically. The [merchant dashboard](https://merchant.payai.network) is the optional human-managed route. See [facilitator authentication](/x402/facilitators/authentication) for package-based and direct HTTP setup.
3. Configure [Bazaar discovery](/x402/facilitators/bazaar) if you want to expose supported discovery metadata. Serving an HTTP endpoint alone does not list it automatically.
4. For variable charges, follow the [dynamic pricing guide](/guides/dynamic-pricing-x402) and validate that the payment authorization covers the accepted terms.
5. Plan for capacity limits, timeouts and uncertain outcomes using the [capacity and recovery guidance](/x402/facilitators/capacity-and-limits). A request timeout does not establish that settlement failed.

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