X402 Api

@x402-api/mcp-server

MCP server that gives Claude, ChatGPT, and any MCP-compatible AI agent access to pay-per-call crypto/DeFi data via the x402 protocol.

8 tools. No API keys. AI agents pay USDC micropayments on Base, per request.

Find this service: Official MCP Registry · Glama · Agent discovery manifest · OpenAPI.

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Tools

Tool	API Endpoint	Cost	Description
get_crypto_prices	GET /api/price-feed	0.001 USDC	BTC/ETH/SOL + top 24h movers
get_gas_prices	GET /api/gas-tracker	0.001 USDC	Multi-chain gas (ETH, Base, Polygon, Arbitrum)
get_dex_quotes	GET /api/dex-quotes	0.002 USDC	One ParaSwap aggregate route
scan_token	GET /api/token-scanner	0.003 USDC	GoPlus security flags and heuristic
track_whales	GET /api/whale-tracker	0.005 USDC	Top-holder sample and supply share
scan_yields	GET /api/yield-scanner	0.005 USDC	DefiLlama pool APYs and TVL
get_funding_rates	GET /api/funding-rates	0.008 USDC	Hyperliquid and dYdX hourly rates
profile_wallet	GET /api/wallet-profiler	0.008 USDC	Observed Blockscout balances; partial coverage

---

Quick Start

Option A: Inspect mode (no payment needed)

Just run it — any 402 responses will return human-readable payment instructions:

npx @x402-api/mcp-server

Claude will tell you what's needed when a tool requires payment.

Option B: Auto-pay mode (fully autonomous)

Install optional payment deps and set your wallet key:

npm install -g @x402-api/mcp-server
npm install -g viem
export X402_WALLET_PRIVATE_KEY=0x<your_private_key>
x402-api-mcp

The MCP server signs Base USDC EIP-3009 authorizations only when the API advertises that settlement mode. The default payment cap is 0.01 USDC per call. Fund the wallet with USDC on Base; the API operator sponsors gas in direct settlement mode.

---

Claude Desktop Integration

Add to your claude_desktop_config.json:

Without auto-pay (inspect mode)

{
  "mcpServers": {
    "x402-api": {
      "command": "npx",
      "args": ["@x402-api/mcp-server"]
    }
  }
}

With auto-pay

{
  "mcpServers": {
    "x402-api": {
      "command": "npx",
      "args": ["@x402-api/mcp-server"],
      "env": {
        "X402_WALLET_PRIVATE_KEY": "0x<your_private_key>"
      }
    }
  }
}

Config file location:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

---

Environment Variables

Variable	Required	Description
X402_WALLET_PRIVATE_KEY	Optional	Base wallet private key for EIP-3009 automatic payment. Requires viem.
X402_MAX_PER_CALL_USDC	Optional	Per-call cap, default 0.01 USDC.
X402_API_BASE_URL	Optional	Override API URL (default: https://x402-api.fly.dev)

---

How x402 Payments Work

This API uses the x402 protocol — HTTP 402 Payment Required:

1. Agent calls tool → MCP server makes API request
2. Server returns 402 with payment details (amount, USDC address, Base network)
3. Auto-pay mode: this client signs an EIP-3009 authorization and retries; the API settles it on Base
4. Inspect mode: MCP returns 402 details without signing or paying

Payment details:

• Token: USDC on Base mainnet
• Address: 0x60264c480b67adb557efEd22Cf0e7ceA792DefB7
• Chain: Base (chain ID 8453)
• Amount: 0.001–0.008 USDC per call (< 1 cent USD)

---

Tool Reference

get_crypto_prices

No parameters. Returns current prices for BTC, ETH, SOL + top 24h movers.

Cost: 0.001 USDC

get_gas_prices

No parameters. Returns gas prices for Ethereum, Base, Polygon, Arbitrum — slow/standard/fast tiers.

Cost: 0.001 USDC

get_dex_quotes

Get one ParaSwap aggregate route. No independent comparison between DEX venues.

Parameter	Type	Required	Description
from	string	✅	Input token (e.g. "ETH", "0x...")
to	string	✅	Output token (e.g. "USDC")
amount	string	✅	Amount to swap (e.g. "1.5")

Cost: 0.002 USDC

scan_token

Token security scan — detects rug-pull flags, honeypot patterns, mint authority, etc.

Parameter	Type	Required	Description
token	string	✅	Contract address or symbol (e.g. "PEPE")

Cost: 0.003 USDC

track_whales

Top-holder sample from GoPlus. Gini and recent transfer history unavailable.

Parameter	Type	Required	Description
token	string	✅	Contract address or symbol

Cost: 0.005 USDC

scan_yields

Top DeFi yield opportunities across Aave, Compound, Morpho, Lido, Pendle, etc.

Parameter	Type	Required	Description
chain	string	❌	Filter by chain: "ethereum", "base", "arbitrum", "polygon"
min_tvl	number	❌	Minimum TVL in USD (e.g. 1000000)

Cost: 0.005 USDC

get_funding_rates

Hourly perpetual funding from Hyperliquid and dYdX v4. Spreads are indicative.

Parameter	Type	Required	Description
asset	string	❌	Asset symbol (e.g. "BTC", "ETH"). All assets if omitted.

Cost: 0.008 USDC

profile_wallet

Observed priced wallet balances and available transaction counts. DeFi positions, PnL and risk score unavailable.

Parameter	Type	Required	Description
address	string	✅	Ethereum/Base wallet address (0x...)

Cost: 0.008 USDC

---

Development

git clone https://github.com/fernsugi/x402-api-mcp-server
cd x402-api-mcp-server

npm install
npm run build
npm start

To test without a payment wallet, simply run and see the 402 responses:

node dist/index.js

---

Links

• x402 API Landing Page
• x402 Protocol
• Base Chain
• ERC-8004 Agent Identity
• Agent #18763 on BaseScan

---

License

MIT

Three runnable workflows

Workflow	Tools	Total USDC
Token check	scan_token + track_whales	0.008
ETH funding	get_funding_rates	0.008
Swap quote + gas	get_dex_quotes + get_gas_prices	0.003

Runnable Node examples start in inspect mode. Each demo has inputs, recorded provider output, coverage limits, a spending cap, and an agent prompt.

Optional X402_REFERRAL_SOURCE labels requests for first-party aggregate attribution (default mcp). It is a hint, not verified caller identity. The API journals no raw payer wallets, IP addresses, or signatures. X402_EXPECTED_PAY_TO pins the payment recipient to the official wallet by default. Tools advertise that auto-pay can spend money and repeated calls can incur another charge.

Cursor / other local MCP clients

Use the same mcpServers configuration shown above. For Cursor, put it in .cursor/mcp.json in your project. Inspect mode needs no wallet. Set X402_MAX_PER_CALL_USDC before enabling auto-pay; repeated calls spend again. Keep wallet credentials in local environment settings, outside Git.

Registry publication

The Publish MCP Registry GitHub workflow validates the matching npm version, then publishes server.json using GitHub OIDC. It runs on a published GitHub release or a manual dispatch from main. No npm token, GitHub PAT, or wallet key is stored in CI. Actions and official publisher source are pinned to verified commits. npm publication still happens separately before creating the release.