Agents Without Cards: Building Self-Paying APIs with x402 and MCP

As AI agents become autonomous economic participants, traditional credit-card-based APIs create friction. x402 solves this by enabling agents to autonomously sign blockchain transactions and pay for API access on-chain. By integrating x402 with MCP servers, developers can build truly automated agent-to-agent marketplaces where payment, verification, and access happen entirely without human intervention—opening a new category of paid services designed for machine actors.