Created on 25th June 2025
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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
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.
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)
Pinata
Technologies used
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