x402 Agent Store

HTTP 402, finally used.

"Payment Required" has been an unused HTTP status code for decades. The x402 protocol puts it to work: a request comes back with a 402, the client pays on-chain, and retries — automatically. I built a marketplace on top of it for n8n workflows, with two payment models: buy a workflow once and download it, or pay per API call to run it.

The callback pattern for long-running agents.

The most interesting problem was AI analyses that take minutes, against serverless functions that time out in a hundred seconds:

• Instead of waiting synchronously, the API hands a job ID to n8n; n8n responds immediately and calls back over a webhook when it finishes, while the frontend polls job status — long analyses that would blow the timeout now complete cleanly.
• Payments flow through an x402 client that handles the 402 automatically, backed by on-chain verification and replay-attack prevention.
• Multi-token support (USDC plus arbitrary SPL tokens) with a fully JSON-configured agent catalog.
• The 12-chapter integration guide I wrote for it is itself listed as a product in the store.