Bounty API

Agent-native data APIs where AI agents pay per request in USDC on Base. Singapore property & financial data, live now.

Live at bountyapi.com

What it does

AI agents discover data APIs via MCP, call them, and pay automatically using x402 micropayments. No API keys. No subscriptions. No scraping. One price per call, known upfront, settled on-chain.

Agent calls GET /company-lookup?name=ACME
  → Server returns 402 Payment Required ($0.05 USDC)
  → Agent signs payment on Base
  → Server returns data + settlement receipt
  → Transaction verifiable on Basescan

Verified working

Real on-chain transaction — an AI agent autonomously paid for data on Base mainnet:

• Tx: 0xc42354ea...
• Amount: $0.01 USDC
• Network: Base (eip155:8453)
• Facilitator: PayAI

Architecture

Layer 1: Raw API endpoints (FastAPI)
  → bountyapi.com/bsd, /hdb/towns, /postal/{code}, etc.

Layer 2: x402 payment middleware
  → Paid endpoints return 402 + payment instructions
  → Agent pays USDC on Base → facilitator verifies → data returned

Layer 3: MCP discovery (npm: bountyapi-mcp)
  → Agents discover APIs as tools via Model Context Protocol
  → Supports both stdio (npx) and HTTP transport (/mcp endpoint)
  → Wallet-aware: auto-pays for paid endpoints when configured

Live APIs (7 endpoints)

API	Type	Price	Description
Stamp Duty (BSD + ABSD)	FREE	$0	Singapore property stamp duty, verified against IRAS
Postal District Lookup	FREE	$0	28 postal districts, mapped from URA source
Mortgage Calculator	FREE	$0	Standard amortization
Compound Interest	FREE	$0	Growth projections
Currency Converter	FREE	$0	30+ currencies, ECB rates
HDB Resale Data	PAID	$0.01/call	Government transaction data from data.gov.sg
Rental Yield Calculator	PAID	$0.005/call	Investment metrics (gross yield, cap rate, cashflow)

Every response carries source provenance. No interpolated or fabricated values.

Quick start

Install the MCP server

npx bountyapi-mcp

With payment support (for paid endpoints)

EVM_PRIVATE_KEY=0x... MAX_SPEND_USD=1.00 npx bountyapi-mcp

Claude Desktop config

{
  "mcpServers": {
    "bounty": {
      "command": "npx",
      "args": ["bountyapi-mcp"],
      "env": {
        "EVM_PRIVATE_KEY": "0x...",
        "MAX_SPEND_USD": "1.00"
      }
    }
  }
}

Then ask Claude: "What's the stamp duty on a $1.5M Singapore property for a first-time buyer?"

Direct API calls (no MCP needed)

# Free endpoint
curl https://bountyapi.com/bsd?price=1500000
# → {"bsd": 44600, "source": "iras.gov.sg"}

# Paid endpoint (returns 402 without payment)
curl https://bountyapi.com/hdb/towns
# → 402 Payment Required + x402 challenge

Tech stack

• Backend: FastAPI (Python), deployed on Railway
• Payments: x402 protocol, USDC on Base, PayAI facilitator
• MCP: TypeScript, @modelcontextprotocol/sdk, @x402/evm
• Data sources: IRAS, URA, data.gov.sg, ECB
• Domain: bountyapi.com (SSL via Railway/Let's Encrypt)

Project structure

├── app.py              # Main FastAPI app, landing page, routes
├── pages.py            # Site pages (pricing, setup, API detail pages)
├── payment.py          # x402 payment middleware config
├── apis/               # API modules (postal, rental, hdb, mortgage, etc.)
├── mcp-server/         # TypeScript MCP server (published to npm)
├── public/             # Favicons, OG images, webmanifest
└── Dockerfile          # Railway deployment

Development

# Backend
pip install -r requirements.txt
uvicorn app:app --reload

# MCP server
cd mcp-server
npm install
npm run build
node dist/index.js

License

MIT