Agent Payment MCP server

🍋 LemonCake

The billing, budget & identity layer for software for agents. Private Beta · Open core

Monetize any MCP/API in minutes, and let AI agents pay for it safely — each agent gets a spend-capped identity (budget, usage, pause/revoke). Buyers pay by card; no crypto wallet. First 3,000 calls free (lifetime). Then 3% only when your API earns.

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🚀 Get started · 💲 Pricing · 📚 Docs · 🌐 Live

☝️ A real AI agent buys API calls by itself ($0.01 each), stops at its cap, and the API owner earns — no human, no crypto. · demo source

🚀 Get started

Monetizing an MCP/API? Start here — one command:

npx create-lemon-mcp my-paid-mcp     # a paid MCP server, running in sandbox now
# then add a Seller Key in /app and set LEMONCAKE_SELLER_KEY → it charges for real (no code change)

Pick your path:

Buyer-side MCP — try in 30 seconds

npx -y agent-payment-mcp

{ "mcpServers": { "lemon": { "command": "npx", "args": ["-y", "agent-payment-mcp"] } } }

Ask your agent to run listdemos / calldemo. To call paid APIs, set LCPAYTOKEN (get one at lemoncake.xyz/app).

What is LemonCake?

LemonCake is an x402 payment rail for monetizing MCP servers and HTTP APIs. Sellers register an endpoint and set a price per call. Buyers prepay by card and receive a spend-capped Pay Token. Agents call the gateway with that token, and LemonCake verifies, meters, forwards, and records usage.

sequenceDiagram
    participant A as 🤖 AI Agent
    participant G as 🍋 LemonCake Gateway
    participant API as Your API
    A->>G: POST /g/:id (no token)
    G-->>A: 402 + accepts[] (price, mintUrl)
    A->>G: mint Pay Token (off-session, capped)
    A->>G: Bearer :jwt
    G->>API: forward (upstream key hidden)
    API-->>A: 200 + result
    Note over A,G: budget exhausted → 402 → agent self-funds → continues

Sellers register any HTTP API and set a price per call. Buyers / agents prepay with a card → Pay Token issued automatically → agent calls the API within budget. Budget exhausted → 402 challenge → agent self-funds → continues. No humans.

🧱 Open core

Shortened. The full README is on GitHub.