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FiscalData Treasury Data API

by U.S. Department of the Treasury

332 txns
5 agents

About

This API provides access to a wide range of public federal financial data, including topics like public debt, revenue, spending, interest rates, and more

Categories

US GovernmentFinancial

Access Data

For AI Agents

MCP Server

Install the x402 MCP server to let your AI agent access this data with automatic USDC payments on Base.

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "x402": {
      "command": "npx",
      "args": ["@serendb/x402-mcp-server"],
      "env": {
        "X402_GATEWAY_URL": "https://api.serendb.com",
        "WALLET_PRIVATE_KEY": "0x..."
      }
    }
  }
}
Claude Code

Replace 0x... with your wallet private key.

macOS / Linux
claude mcp add x402 \
  -e X402_GATEWAY_URL=https://api.serendb.com \
  -e WALLET_PRIVATE_KEY=0x... \
  -- npx -y @serendb/x402-mcp-server
Windows (PowerShell)
claude mcp add x402 `
  -e X402_GATEWAY_URL=https://api.serendb.com `
  -e WALLET_PRIVATE_KEY=0x... `
  '--' npx -y @serendb/x402-mcp-server
Gemini CLI

Replace 0x... with your wallet private key.

gemini mcp add x402 \
  -e X402_GATEWAY_URL=https://api.serendb.com \
  -e WALLET_PRIVATE_KEY=0x... \
  -- npx -y @serendb/x402-mcp-server
Codex CLI

Replace 0x... with your wallet private key.

codex mcp add x402 \
  --env X402_GATEWAY_URL=https://api.serendb.com \
  --env WALLET_PRIVATE_KEY=0x... \
  -- npx -y @serendb/x402-mcp-server
Cursor

Important: Cursor has a 60s timeout. Pre-install globally first: npm install -g @serendb/x402-mcp-server

First, install globally to avoid timeout issues:

npm install -g @serendb/x402-mcp-server

Then add to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "x402": {
      "command": "x402-mcp-server",
      "args": [],
      "env": {
        "X402_GATEWAY_URL": "https://api.serendb.com",
        "WALLET_PRIVATE_KEY": "0x..."
      }
    }
  }
}

Also works with Windsurf, Zed, and other MCP-compatible clients. See the full setup guide for details.

Full Setup Guidenpm Package

For Developers

Direct HTTP API

Access data directly via HTTP using the x402 payment protocol.

How x402 Payments Work
  1. Send your query request to the gateway
  2. Receive HTTP 402 with payment requirements (amount, wallet, EIP-712 data)
  3. Sign the payment authorization with your wallet
  4. Retry request with X-PAYMENT header containing the signature
  5. Receive your data - payment settles automatically via USDC on Base
Step 1: Get Payment Requirements
curl -X POST https://api.serendb.com/agent/api \
  -H "Content-Type: application/json" \
  -d '{
    "publisherId": "cd9118d8-9b32-47cd-b0e1-52419533774c",
    "agentWallet": "0xYourWalletAddress",
    "request": {
      "method": "GET",
      "path": "/endpoint"
    }
  }'

This returns 402 Payment Required with the payment details you need to sign.

Step 2: Add Payment Header

After signing the EIP-712 authorization, add the base64-encoded signature:

curl -X POST https://api.serendb.com/agent/api \
  -H "Content-Type: application/json" \
  -H "X-PAYMENT: <base64-encoded-signature>" \
  -d '{ ... }'
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Pricing

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Publisher Details

Type: api
Added: November 30, 2025
Cache TTL: 300s