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This example demonstrates the simplest way to integrate Snack Money payments using axios with the x402 v2 payment client. Perfect for most web applications.

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Overview

@x402/axios v2 wraps the popular axios HTTP client with automatic x402 payment negotiation. When the API returns 402 Payment Required, the client handles the payment flow automatically.

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Features

  • ✅ Base (EVM) and Solana (SVM) network support
  • ✅ Automatic payment negotiation
  • ✅ Simple axios-based API
  • ✅ Type-safe TypeScript
  • ✅ Minimal setup

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Prerequisites

  • Node.js 18+
  • USDC balance on Base or Solana network
  • EVM private key (for Base) or SVM private key (for Solana)

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Installation

npm install axios @x402/axios @x402/evm @x402/svm viem

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Quick Start

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1. Set Up Environment

Create a .env file: 
# For Base network
EVM_PRIVATE_KEY=0x...
# For Solana network
SVM_PRIVATE_KEY=base58_key...
# Common
RECEIVER=your_x_username
AMOUNT=0.01
Important: Use your own X (Twitter) account as the receiver to test the integration safely.

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2. Implement Base (EVM) Payment

Create base-send.ts: 
import axios from "axios";
import { privateKeyToAccount } from "viem/accounts";
import {
  x402Client,
  wrapAxiosWithPayment,
  decodePaymentResponseHeader,
} from "@x402/axios";
import { registerExactEvmScheme } from "@x402/evm/exact/client";

// Load environment variables
const evmPrivateKey = process.env.EVM_PRIVATE_KEY as `0x${string}`;
const receiver = process.env.RECEIVER as string;
const amount = parseFloat(process.env.AMOUNT || "0.01");

async function sendPayment() {
  console.log("🚀 Starting Snack Money payment example with x402-axios v2\n");
  console.log("ℹ️  Network: Base (EVM)\n");

  // Create Base signer
  const evmAccount = privateKeyToAccount(evmPrivateKey);
  console.log("✅ Base signer created:", evmAccount.address);

  // Create x402 client and register EVM scheme
  const client = new x402Client();
  registerExactEvmScheme(client, { signer: evmAccount });
  console.log("✅ Registered EVM payment scheme\n");

  // Create axios instance with x402 payment interceptor
  const api = wrapAxiosWithPayment(
    axios.create({ baseURL: "https://api.snack.money" }),
    client
  );

  console.log(`💸 Sending ${amount} USDC to @${receiver} on X via Base...\n`);

  try {
    const response = await api.post("/payments/x/pay", {
      amount,
      currency: "USDC",
      receiver,
      description: "Payment via x402-axios v2 (Base)"
    });

    console.log("✅ Payment successful!");
    console.log("\n📊 Response:", JSON.stringify(response.data, null, 2));

    // Decode and display payment response header (v2 uses payment-response)
    const paymentResponseHeader = response.headers["payment-response"];
    if (paymentResponseHeader) {
      const paymentResponse = decodePaymentResponseHeader(paymentResponseHeader);
      console.log("\n🔐 Payment Response Details:", JSON.stringify(paymentResponse, null, 2));
    }
  } catch (error) {
    console.error("❌ Payment failed:", error);
    throw error;
  }
}

sendPayment();

​
3. Implement Solana (SVM) Payment

Create solana-send.ts: 
import axios from "axios";
import {
  x402Client,
  wrapAxiosWithPayment,
  decodePaymentResponseHeader,
} from "@x402/axios";
import { registerExactSvmScheme } from "@x402/svm/exact/client";
import { createKeyPairSignerFromBytes } from "@solana/kit";
import bs58 from "bs58";

// Load environment variables
const svmPrivateKey = process.env.SVM_PRIVATE_KEY as string;
const receiver = process.env.RECEIVER as string;
const amount = parseFloat(process.env.AMOUNT || "0.01");

async function sendPayment() {
  console.log("🚀 Starting Snack Money payment example with x402-axios v2\n");
  console.log("ℹ️  Network: Solana (SVM)\n");

  // Create Solana signer
  console.log("🔧 Creating Solana signer...");
  const privateKeyBytes = bs58.decode(svmPrivateKey);
  const solanaSigner = await createKeyPairSignerFromBytes(privateKeyBytes);
  console.log("✅ Solana signer created:", solanaSigner.address);

  // Create x402 client and register Solana scheme
  const client = new x402Client();
  registerExactSvmScheme(client, { signer: solanaSigner });
  console.log("✅ Registered Solana payment scheme\n");

  // Create axios instance with x402 payment interceptor
  const api = wrapAxiosWithPayment(
    axios.create({ baseURL: "https://api.snack.money" }),
    client
  );

  console.log(`💸 Sending ${amount} USDC to @${receiver} on X via Solana...\n`);

  try {
    const response = await api.post("/payments/x/pay", {
      amount,
      currency: "USDC",
      receiver,
      description: "Payment via x402-axios v2 (Solana)"
    });

    console.log("✅ Payment successful!");
    console.log("\n📊 Response:", JSON.stringify(response.data, null, 2));

    // Decode and display payment response header
    const paymentResponseHeader = response.headers["payment-response"];
    if (paymentResponseHeader) {
      const paymentResponse = decodePaymentResponseHeader(paymentResponseHeader);
      console.log("\n🔐 Payment Response Details:", JSON.stringify(paymentResponse, null, 2));
    }
  } catch (error) {
    console.error("❌ Payment failed:", error);
    throw error;
  }
}

sendPayment();

​
4. Run the Example

For Base network: 
npm run base
# or
npx tsx base-send.ts
For Solana network: 
npm run solana
# or
npx tsx solana-send.ts

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Expected Output

🚀 Starting Snack Money payment example with x402-axios

✅ Base signer created
💸 Sending 0.01 USDC to @username on X...

✅ Payment successful!

📊 Response: {
  "code": 200,
  "msg": "0.01 USDC sent successfully",
  "data": {
    "txn_id": "0xabc...def",
    "amount": 0.01,
    "receipt": "https://snack.money/x/username?txn=..."
  }
}

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How It Works

  1. Create Signer: Generate account from your private key (EVM or SVM)
  2. Create x402 Client: Initialize the x402 client
  3. Register Scheme: Register the appropriate payment scheme (EVM or SVM)
  4. Wrap Axios: Add x402 payment wrapper
  5. Make Request: POST to /payments/x/pay
  6. Auto Payment: Client handles 402 response automatically
  7. Retry: Request retries with payment proof
  8. Success: Receive confirmation and receipt

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Supported Endpoints

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X (Twitter) Payments

await api.post("/payments/x/pay", {
  amount: 0.01,
  currency: "USDC",
  receiver: "username",
  description: "Payment description"
});

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Farcaster Payments

await api.post("/payments/farcaster/pay", {
  amount: 0.5,
  currency: "USDC",
  receiver: "username",
  description: "Payment description"
});

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GitHub Payments

await api.post("/payments/github/pay", {
  amount: 1.0,
  currency: "USDC",
  receiver: "username",
  description: "Payment description"
});

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Configuration Options

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Custom Axios Instance

const api = withPaymentInterceptor(
  axios.create({
    baseURL: "https://api.snack.money",
    timeout: 30000,
    headers: {
      "Content-Type": "application/json"
    }
  }),
  account as never
);

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Request Options

const response = await api.post(
  "/payments/x/pay",
  {
    amount: 0.01,
    currency: "USDC",
    receiver: "username",
    description: "Payment description"
  },
  {
    timeout: 60000  // Custom timeout for this request
  }
);

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Error Handling

try {
  const response = await api.post("/payments/x/pay", {
    amount: 0.01,
    currency: "USDC",
    receiver: "username"
  });

  console.log("Payment successful:", response.data);
} catch (error) {
  if (axios.isAxiosError(error)) {
    if (error.response?.status === 402) {
      console.error("Payment required but failed to process");
    } else if (error.response?.status === 404) {
      console.error("User not found");
    } else {
      console.error("API error:", error.response?.data);
    }
  } else {
    console.error("Unexpected error:", error);
  }
}

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Common Errors

Insufficient USDC Balance 
Ensure your wallet has enough USDC on Base network.
Check balance at: https://basescan.org/
Invalid Private Key 
Private key must be a valid hex string starting with 0x
Format: 0x followed by 64 hex characters
User Not Found 
The receiver username doesn't exist on the platform.
Verify the username is correct.

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Testing Tips

  1. Start small: Use 0.01 USDC for initial tests
  2. Test on yourself: Send to your own X account
  3. Check balance: Verify USDC balance before sending
  4. Save receipts: Keep receipt URLs for records

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Full Example Repository

View the complete example with configuration files: View on GitHub → The repository includes:
  • Complete TypeScript implementation
  • Environment configuration template
  • package.json with all dependencies
  • Detailed README

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Next Steps

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Dependencies

{
  "dependencies": {
    "axios": "^1.7.9",
    "@x402/axios": "^2.0.0",
    "@x402/evm": "^2.0.0",
    "@x402/svm": "^2.0.0",
    "viem": "^2.39.3",
    "bs58": "^6.0.0",
    "dotenv": "^16.4.7"
  },
  "devDependencies": {
    "@types/bs58": "^5.0.0",
    "@types/node": "^22.0.0",
    "typescript": "^5.9.0"
  }
}

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