AgentPay — Ditch those API keys.

Pay per call. No subscriptions. No human in the loop.

AgentPay is an x402 payment gateway for AI agents. Access 12 crypto data tools using USDC on Stellar or Base — agents discover, pay, and get data back autonomously. Agents discover tools, pay per call ($0.001–$0.005), and get real data back — all within a hard budget cap.

→ 12 live tools: token prices, whale activity, gas tracker, DeFi TVL, Fear & Greed, yield scanner, funding rates, token security, Dune queries and more → Budget-aware Session: agents estimate costs, track spend, never exceed budget → x402 protocol: works with any x402-compatible agent → Stellar + Base: pay with USDC on either network — Stellar (5s, $0.00001 fee) or Base mainnet (2s, $0.0001 fee) → No XLM needed: Stellar gas fees are sponsored by the OpenZeppelin x402 Facilitator — agents only need USDC

Live gateway (mainnet): https://gateway-production-2cc2.up.railway.app

---

Quickstart — 3 steps

Step 1: Get a wallet with USDC

Option A — Stellar mainnet (recommended)

Send USDC to a Stellar wallet via Coinbase, Lobstr, or any Stellar DEX. Then use your Stellar secret key (S...) directly.

USDC issuer on Stellar mainnet: GA5ZSEJYB37JRC5AVCIA5MOP4RHTM335X2KGX3IHOJAPP5RE34K4KZVN Gateway: https://gateway-production-2cc2.up.railway.app — use network="mainnet"

Option A — Base mainnet (alternative)

Send USDC to an EVM wallet on Base. Use your EVM private key with network="base".

USDC contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 Gateway: https://gateway-production-2cc2.up.railway.app — use network="base"

Option B — Testnet (free, no wallet needed)

One command gives you a Stellar testnet wallet pre-loaded with 5 USDC:

curl https://gateway-testnet-production.up.railway.app/faucet

Use network="testnet" and gateway_url="https://gateway-testnet-production.up.railway.app" in your Session.

---

Step 2: Create a Session with a budget

from agent.wallet import AgentWallet, Session, BudgetExceeded

# Option A — Stellar mainnet
wallet = AgentWallet(secret_key="S...", network="mainnet")
GATEWAY = "https://gateway-production-2cc2.up.railway.app"

# Option B — Testnet (faucet wallet)
# wallet = AgentWallet(secret_key="S...", network="testnet")
# GATEWAY = "https://gateway-testnet-production.up.railway.app"

with Session(wallet=wallet, gateway_url=GATEWAY, max_spend="0.05") as session:
    print(f"Balance:  {wallet.get_usdc_balance()} USDC")
    print(f"Budget:   {session.remaining()} remaining")

The Session enforces a hard USDC cap across all calls. It raises BudgetExceeded before any payment goes out if a tool would push you over, and automatically falls back to the next-cheapest tool in the same category when the preferred one is too expensive.

---

Step 3: Call tools — payment is automatic

with Session(wallet=wallet, gateway_url=GATEWAY, max_spend="0.05") as session:

    # Token price — $0.001
    r = session.call("token_price", {"symbol": "ETH"})
    print(f"ETH: ${r['price_usd']:,.2f}  ({r['change_24h_pct']:+.2f}% 24h)")

    # Fear & Greed Index — $0.001
    r = session.call("fear_greed_index", {"limit": 1})
    print(f"Sentiment: {r['value']}/100 — {r['value_classification']}")

    # DeFi TVL — $0.002
    r = session.call("defi_tvl", {"protocol": "aave"})
    print(f"Aave TVL: ${r['tvl'] / 1e9:.1f}B  ({r['change_1d']:+.1f}% 24h)")

    # Crypto news — $0.003
    r = session.call("crypto_news", {"currencies": "ETH", "filter": "hot"})
    for h in r["headlines"][:3]:
        print(f"  [{h['sentiment']:>7}] {h['title'][:55]}")

    print(f"\nTotal spent: {session.spent()}")
    print(f"Remaining:   {session.remaining()}")

Each session.call() handles the full x402 flow internally:

1. Checks your remaining budget against the tool's price (pre-flight, no payment yet)
2. POSTs to the gateway, receives a 402 with {payment_id, amount_usdc, pay_to}
3. Sends USDC on Stellar — ~2–3 seconds on testnet
4. Retries the request with X-Payment: tx_hash=<hash>,from=<addr>,id=<payment_id>
5. Returns the data

---

Available Tools

Tool	Price	Parameters	Returns
token_price	$0.001	symbol (BTC, ETH, SOL…)	price_usd, change_24h_pct, market_cap_usd
gas_tracker	$0.001	—	slow/standard/fast gwei, base_fee_gwei
fear_greed_index	$0.001	limit (days of history, default 1)	value 0–100, value_classification, history[ ]
wallet_balance	$0.002	address, chain (ethereum/stellar)	token balances
whale_activity	$0.002	token, min_usd (default 100k)	large_transfers[ ], total_volume_usd
defi_tvl	$0.002	protocol (optional, e.g. "uniswap")	tvl, change_1d, change_7d, chains[ ]
token_security	$0.002	contract_address, chain (ethereum/bsc)	risk_level, is_honeypot, buy_tax, sell_tax, holder_count
yield_scanner	$0.004	token, chain (optional), min_tvl (default $1M)	top 10 pools by APY with protocol, tvl_usd, risk_level
dex_liquidity	$0.003	token_a, token_b	volume_24h_usd, market_cap_usd, ath_usd
funding_rates	$0.003	asset (optional, e.g. "BTC")	funding_rate_pct, annualized_rate_pct, sentiment per exchange
crypto_news	$0.003	currencies (e.g. "ETH,BTC"), filter (hot/new/rising)	headlines[ ] with title, url, sentiment, score
dune_query	$0.005	query_id, limit (default 25)	rows[ ], columns[ ], row_count from Dune Analytics

Discover all tools dynamically:

import httpx
tools = httpx.get(f"{GATEWAY}/tools").json()["tools"]
for t in tools:
    print(f"{t['name']:<22} ${t['price_usdc']}  — {t['description']}")

---

Payment Options

AgentPay accepts USDC payments on two networks:

• Stellar — $0.00001 per tx, 5-second settlement (recommended for agents using the Python SDK)
• Base — $0.0001 per tx, 2-second settlement (EIP-3009 transferWithAuthorization on Base mainnet)

The gateway's 402 response advertises both options simultaneously. Clients pick the network that suits them — no configuration required on the tool side.

OpenZeppelin x402 Facilitator (Stellar)

Stellar payments are verified through the OpenZeppelin x402 Facilitator, which sponsors XLM gas fees on behalf of agent wallets. This means agents only need USDC — no need to separately acquire XLM to pay for transaction fees.

Endpoint	URL
Mainnet	https://channels.openzeppelin.com/x402
Testnet	https://channels.openzeppelin.com/x402/testnet

The facilitator exposes /verify and /settle — the gateway calls /verify with the payment details and receives {"isValid": true, "txHash": "..."} in return. This replaces the previous approach of polling Stellar Horizon directly.

{
  "payment_options": {
    "stellar": { "pay_to": "G...", "amount_usdc": "0.001", ... },
    "base":    { "network": "eip155:8453", "asset": "0x833589f...", "amount_usdc": "0.001", ... }
  }
}

Base payments use Mode B direct on-chain settlement: the client calls transferWithAuthorization on the USDC contract and sends the tx_hash in the PAYMENT-SIGNATURE header. The gateway verifies the receipt via JSON-RPC.

---

MCP Server

AgentPay ships a Model Context Protocol server that gives Claude Desktop direct access to all 12 tools. Payments happen automatically in the background using Stellar USDC.

See README_MCP.md for setup instructions.

Quick config (claude_desktop_config.json):

{
  "mcpServers": {
    "agentpay": {
      "command": "python",
      "args": ["/path/to/agentpay/gateway/mcp_server.py"],
      "env": {
        "STELLAR_SECRET_KEY": "S...",
        "AGENTPAY_GATEWAY_URL": "https://gateway-production-2cc2.up.railway.app"
      }
    }
  }
}

---

Without the SDK — raw HTTP

The x402 flow works with any HTTP client in any language.

GATEWAY="https://gateway-production-2cc2.up.railway.app"
AGENT_ADDR="G..."   # your Stellar public key

# 1. Call the tool → receive 402 payment challenge
RESPONSE=$(curl -s -X POST "$GATEWAY/tools/token_price/call" \
  -H "Content-Type: application/json" \
  -d "{\"parameters\":{\"symbol\":\"ETH\"},\"agent_address\":\"$AGENT_ADDR\"}")

PAYMENT_ID=$(echo $RESPONSE | python3 -c "import sys,json; print(json.load(sys.stdin)['payment_id'])")
AMOUNT=$(echo $RESPONSE    | python3 -c "import sys,json; print(json.load(sys.stdin)['amount_usdc'])")
PAY_TO=$(echo $RESPONSE    | python3 -c "import sys,json; print(json.load(sys.stdin)['pay_to'])")

# 2. Send USDC on Stellar (memo = first 28 chars of payment_id)
TX_HASH=$(python3 -c "
from stellar_sdk import Keypair, Server, Network, Asset, TransactionBuilder
kp = Keypair.from_secret('S...')
server = Server('https://horizon-testnet.stellar.org')
acct = server.load_account(kp.public_key)
tx = (TransactionBuilder(acct, Network.TESTNET_NETWORK_PASSPHRASE, base_fee=100)
      .add_text_memo('$PAYMENT_ID'[:28])
      .append_payment_op('$PAY_TO', Asset('USDC','GBBD47IF6LWK7P7MDEVSCWR7DPUWV3NY3DTQEVFL4NAT4AQH3ZLLFLA5'), '$AMOUNT')
      .set_timeout(30).build())
tx.sign(kp)
print(server.submit_transaction(tx)['hash'])
")

# 3. Retry with payment proof → get data
curl -s -X POST "$GATEWAY/tools/token_price/call" \
  -H "Content-Type: application/json" \
  -H "X-Payment: tx_hash=$TX_HASH,from=$AGENT_ADDR,id=$PAYMENT_ID" \
  -d "{\"parameters\":{\"symbol\":\"ETH\"},\"agent_address\":\"$AGENT_ADDR\"}"

---

Session API reference

# Pre-check price without paying
price = session.estimate("dune_query")       # "$0.005"

# Check headroom before committing
if not session.would_exceed("0.005"):
    result = session.call("dune_query", {"query_id": 3810512, "limit": 10})

# Access spend state mid-session
session.spent()        # "$0.004"
session.remaining()    # "$0.046"

# Full breakdown after session closes
summary = session.summary()
# {
#   "calls": 3,
#   "spent_usdc": "0.006",
#   "spent_fmt": "$0.006",
#   "remaining_fmt": "$0.044",
#   "breakdown": [
#     {"tool": "token_price", "amount_usdc": "0.001", "tx_hash": "abc123..."},
#     {"tool": "gas_tracker",  "amount_usdc": "0.001", "tx_hash": "def456..."},
#     {"tool": "defi_tvl",     "amount_usdc": "0.002", "tx_hash": "ghi789..."}
#   ]
# }

---

Run the demo

git clone <this-repo> && cd agentpay
python -m venv venv && source venv/bin/activate
pip install -r requirements.txt

# Copy env and add your Stellar secret key
cp .env.example .env

# Run the full 5-tool ETH analysis against the live gateway
AGENTPAY_GATEWAY_URL=https://gateway-production-2cc2.up.railway.app \
  python agent/budget_demo.py

Expected output: ETH price, gas, DEX liquidity, whale moves, and Dune onchain data — all paid for autonomously in ~$0.012 USDC.

---

Architecture

agent (Python SDK)
    │
    │  POST /tools/{name}/call
    │  ← 402 {payment_options: {stellar: {...}, base: {...}}}
    │  → Stellar USDC payment (~3s)  OR  Base transferWithAuthorization (~2s)
    │  → retry with X-Payment or PAYMENT-SIGNATURE header
    │  ← 200 {result: ...}
    ▼
gateway (FastAPI on Railway)
    │
    ├── registry/registry.py   — 12-tool catalog with prices & dev wallets
    ├── gateway/stellar.py     — Stellar payment verification via OZ x402 Facilitator (no XLM for gas)
    ├── gateway/base.py        — Base payment verification via JSON-RPC
    └── gateway/main.py        — real API dispatchers
            ├── CoinGecko      token_price, dex_liquidity
            ├── Etherscan V2   gas_tracker, whale_activity, wallet_balance
            ├── DeFiLlama      defi_tvl
            ├── alternative.me fear_greed_index
            ├── Reddit         crypto_news
            ├── Dune Analytics dune_query
            ├── GoPlus         token_security
            ├── DeFiLlama      yield_scanner
            └── Binance/Bybit/OKX funding_rates

Fee model: Gateway charges 15% (GATEWAY_FEE_PERCENT=0.15), forwards the rest to each tool developer's Stellar wallet. All payments settle on-chain in ~2–5 seconds.

Note: Stellar verification uses the OpenZeppelin x402 Facilitator (deployed April 2026). Agents need USDC only — XLM gas fees are sponsored by the facilitator.

---

Discovery

Directories & Listings

Directory	Status
x402scout	✅ indexed, health-checked every 15min
Glama MCP	✅ listed
402index.io	✅ 12 tools registered
awesome-x402	✅ listed
npm	✅ @romudille/agentpay-mcp v1.0.3
xpay.tools	🔜 submission in progress

Agent-Readable Endpoints

AgentPay is discoverable by autonomous agents at standard well-known paths:

Endpoint	Purpose
/.well-known/agentpay.json	AgentPay manifest
/.well-known/agent.json	A2A agent card
/.well-known/l402-services	402index.io discovery format
/llms.txt	LLM-readable service description (tools + integration guide)
/sitemap.xml	17-URL sitemap

Any x402-compatible agent can discover and use AgentPay tools without human setup.