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MCPay.fun

MCPay.fun

Monetize MCP servers in one click

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Built at Coinbase Agents in Action Hackathon

Created on 25th June 2025

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MCPay.fun

MCPay.fun

Monetize MCP servers in one click

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The problem MCPay.fun solves

Developers still burn hours wiring Stripe, API keys, and OAuth just to charge a few cents for an API call. End-users hate paywalls and recurring subscriptions, while machine users (LLMs, autonomous agents) simply can’t enter credit-card forms at all. MCPay.fun flips that model on its head:

  • Pay-per-use APIs & tools – any HTTP endpoint can answer with

    402 Payment Required

    and a USD-price; the MCPay proxy & SDK auto-pay in USDC and replay the call, no keys required (MCPay GitHub)

  • Zero-friction monetization for builders – a server owner sets one price in the registry UI and starts collecting on-chain revenue instantly

  • Agent-native settlement layer – AI agents can chain calls across multiple MCP servers (finance quotes, IPFS uploads, etc.) because payments clear in milliseconds over x402

  • Safer for everyone – stablecoin rails on Base mean ~$0.01 fees and finality in a single block; no hot keys leak to the frontend, because CDP Wallet signs on the server side only.

With one registry, one proxy, and one line of SDK code, MCPay brings real micropayments to the Model Context Protocol.

Challenges I ran into

  • MCP 402 handshake – The official HTTP Streamable transport does not support payments, so I decided to create an extension of this transport to support x402 payments by intercepting HTTP 402 status code requests.

  • Dynamic pricing: It still remains a largely unsolved problem for me how to deal with dynamic payments in MCP sessions and how developers can setup dynamic pricing for different types of tools.

Tracks Applied (3)

Best Use of x402pay + CDPWallet

I wrote a CDP-enabled agent in mcp-examples/agent-cdp. Here’s how the stack comes together. The MCPay proxy sits in fro...Read More

Best Use of x402pay

First, the end-to-end flow: when a request hits a service behind MCPay, the server answers with 402 Payment Required plu...Read More

Best Agentic Use of Pinata

I dropped a full Pinata MCP server into mcp-examples/pinata.cloud. Here’s what it brings to the “Best Agentic Use of Pi...Read More

Pinata

Technologies used

React

Node.js

JavaScript

Next.js

PostgreSQL

Tailwind CSS

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