MCPs/APIs infrastructure: x402 payments & plugins.

🧩 About

As payments rails for agent scale, there's no native way to monetize and authenticate usage for MCP Servers. MCPay provides open-source infrastructure that plugs into any MCP (or API), enabling payments via x402. It enables MCP clients (such as ChatGPT, Cursor, and others) to make pay-per-call requests instead of relying on static subscriptions or API keys. Developers turn agent endpoints into revenue-generating products in minutes, while clients (humans or agents) pay per use. Around the open SDK, we’re building proprietary plugins that extend the basic capabilities.

⚙️ Technical Architecture

MCPay runs on the x402 payment protocol that manages on-chain payments, request retries, and event streaming. It acts as a proxy layer between wallets, clients, and MCP servers.

It uses stablecoins (like USDC) on all supported networks. On EVM, we support Base, Avalanche, Iotex, Sei and Polygon. We also support Solana. For wallets we use Coinbase Developer Platform embedded wallets and also support Coinbase Onramp.

The infrastructure is modular allowing new chains, facilitators, wallets or auth providers to be easily supported:

💼 Business Model

Our strategy is to offer an open-source core proxy that attracts developers and eliminates closed-source alternatives. Around this core, we're building proprietary, monetized plugins that extend MCP capabilities.

This approach creates an ecosystem around MCPay, where each plugin is an independent product that can integrate with any MCP (with or without MCPay).

Our target users are developers building MCPs and online businesses offering APIs that want to make their services accessible to agents.