> ## 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.

> Choose a language and framework to start accepting or making x402 payments with PayAI.

# Quickstart

This page gets you set up quickly as a merchant (server) or a buyer (client).

If your goal is to let AI agents pay for an API or SaaS operation, start with [Accept payments from AI agents](/guides/accept-payments-from-ai-agents) for the end-to-end path.

For a complete Mainnet merchant and guarded buyer, choose [Base Express](/x402/base-mainnet-express) with upstream `@x402/evm` or [Solana Express](/x402/solana-mainnet-express) with `@x402/svm`.

Choose your language and framework below to get started.

<Note>[Scroll to the end to see all supported blockchain networks.](#supported-networks)</Note>

## Servers (Merchants)

<Tabs>
  <Tab title="TypeScript">
    <CardGroup>
      <Card title="Express" href="/x402/servers/typescript/express" icon="server">
        Quickstart for building an x402-enabled server with Express.
      </Card>

      <Card title="Hono" href="/x402/servers/typescript/hono" icon="server">
        Quickstart for building an x402-enabled server with Hono.
      </Card>

      <Card title="NextJS" href="/x402/servers/typescript/nextjs" icon="server">
        NextJS server quickstart is coming soon.
      </Card>
    </CardGroup>
  </Tab>

  <Tab title="Python">
    <CardGroup>
      <Card title="FastAPI" href="/x402/servers/python/fastapi" icon="server">
        Quickstart for building an x402-enabled server with FastAPI.
      </Card>

      <Card title="Flask" href="/x402/servers/python/flask" icon="server">
        Quickstart for building an x402-enabled server with Flask.
      </Card>
    </CardGroup>
  </Tab>
</Tabs>

## Clients (Buyers)

<Tabs>
  <Tab title="TypeScript">
    <CardGroup>
      <Card title="Axios" href="/x402/clients/typescript/axios" icon="code">
        Quickstart for building an x402 client with Axios.
      </Card>

      <Card title="Fetch" href="/x402/clients/typescript/fetch" icon="code">
        Quickstart for building an x402 client with Fetch.
      </Card>
    </CardGroup>
  </Tab>

  <Tab title="Python">
    <CardGroup>
      <Card title="httpx" href="/x402/clients/python/httpx" icon="code">
        Quickstart for building an x402 client with httpx.
      </Card>

      <Card title="requests" href="/x402/clients/python/requests" icon="code">
        Quickstart for building an x402 client with requests.
      </Card>
    </CardGroup>
  </Tab>
</Tabs>

## Facilitator

The TypeScript guides use `@payai/facilitator`, which automatically connects to the PayAI facilitator at `https://facilitator.payai.network`. No manual URL configuration needed.

```typescript theme={null}
import { facilitator } from "@payai/facilitator";
import { HTTPFacilitatorClient } from "@x402/core/server";

const facilitatorClient = new HTTPFacilitatorClient(facilitator);
```

The facilitator works immediately for ordinary exact payments, including mainnet production traffic within the [free allowance](/x402/facilitators/pricing). No API key or portal signup is required to launch. When you need paid capacity beyond the allowance, an autonomous agent can [buy credits and receive an API key over x402](/x402/facilitators/agent-api-keys); the paying wallet gets a wallet-owned agent account programmatically. You can also use the optional [merchant dashboard](https://merchant.payai.network). Then set `PAYAI_API_KEY_ID` and `PAYAI_API_KEY_SECRET` to authenticate.

The PayAI facilitator supports the following endpoints:

* `/supported` - see which networks and schemes are supported
* `/verify` - verify that a payment is valid
* `/settle` - settle the payment
* `/discovery/resources` - view the bazaar, a marketplace of merchants

Read the [reference](/x402/reference#7-1-post-%2Fverify) for more information on the facilitator endpoints and responses.

## Supported networks

The PayAI facilitator supports x402 on the following networks:

| Network Name | V1 Network String | V2 CAIP-2 ID |
| - | - | - |
| Arbitrum One | `arbitrum` | `eip155:42161` |
| Arbitrum Sepolia | `arbitrum-sepolia` | `eip155:421614` |
| Avalanche | `avalanche` | `eip155:43114` |
| Avalanche Fuji | `avalanche-fuji` | `eip155:43113` |
| Base | `base` | `eip155:8453` |
| Base Sepolia | `base-sepolia` | `eip155:84532` |
| Polygon | `polygon` | `eip155:137` |
| Polygon Amoy | `polygon-amoy` | `eip155:80002` |
| Sei | `sei` | `eip155:1329` |
| Sei Testnet | `sei-testnet` | `eip155:713715` |
| SKALE Base | `skale-base` | `eip155:1187947933` |
| SKALE Base Sepolia | `skale-base-sepolia` | `eip155:324705682` |
| Solana | `solana` | `solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp` |
| Solana Devnet | `solana-devnet` | `solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1` |
| X Layer | `xlayer` | `eip155:196` |
| X Layer Testnet | `xlayer-testnet` | `eip155:1952` |

## Need help?

<Card title="Join our Community" icon="discord" href="https://discord.gg/eWJRwMpebQ">
  Have questions or want to connect with other developers? Join our Discord server.
</Card>


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