x402

The x402 standard is an open, HTTP-based payment protocol developed by Coinbase. It uses the HTTP 402 status code (Payment Required) to enable instant, on-chain micropayments directly over the web.

No API keys. No registration. No OAuth. Just pay per request with your wallet. See x402.org.

Available Endpoints

Indigo Chat

POST /v1/agents/indigo

Chat with the Indigo AI agent for real-time market insights and narrative analysis.

{
  "messages": [
    {
      "role": "user",
      "content": "Which developing narrative has the most potential for growth?"
    }
  ]
}

This works like a standard LLM completions endpoint. Each request is stateless, so if you want the agent to have context from prior exchanges, include the conversation history in the messages array:

{
  "messages": [
    {
      "role": "user",
      "content": "Which developing narrative has the most potential for growth?"
    },
    {
      "role": "assistant",
      "content": "Based on current momentum, ..."
    },
    {
      "role": "user",
      "content": "What are the main risks with that narrative?"
    }
  ]
}

Surging Projects

GET /v1/projects

Retrieve the list of projects with surging momentum, updated in real time.

How It Works

1. Make a request to an x402-enabled endpoint
2. Receive a 402 Payment Required response with payment details
3. Authorize the payment on-chain with your wallet
4. Retry the request with payment proof
5. Receive the data

The x402 helper libraries handle steps 2-4 automatically. You make a single request and get the response—payment happens transparently.

Integration

Use the x402-fetch or x402-axios packages to wrap your HTTP client with automatic payment handling:

npm install x402-fetch viem

import { wrapFetchWithPayment } from 'x402-fetch'
import { privateKeyToAccount } from 'viem/accounts'

const account = privateKeyToAccount(process.env.WALLET_PRIVATE_KEY)
const fetchWithPayment = wrapFetchWithPayment(fetch, account)

const response = await fetchWithPayment(
  'https://api.aixbt.tech/x402/v1/agents/indigo',
  {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      messages: [
        { role: 'user', content: 'What narratives are gaining traction?' },
      ],
    }),
  },
)

For complete examples using both fetch and axios, see the AIXBT x402 Examples repository.

Automatic Refunds

If a request fails to return meaningful results, you receive an automatic on-chain refund. This applies to:

• 404 errors — No information found for your query
• 500 errors — Server encountered an internal error

The refund response includes a transaction hash you can verify on-chain:

{
  status: 404,
  error: "No information found",
  data: {
    message: "The request was processed but no meaningful information was found.",
    refund: {
      attempted: true,
      successful: true,
      transactionHash: "0x...",
      reason: "No information found"
    }
  }
}

Try It

Explore available endpoints and test them directly on x402scan.

Resources

• x402 Protocol — Protocol specification
• AIXBT x402 Examples — Implementation examples
• x402 Quickstart for Buyers — Coinbase documentation