How to Build an Agent Marketplace: The Technical Architecture

Description and use

A fully automated agent marketplace architecture: machine‑readable listings, programmatic x402 payments, trust via proof chains, and instant USDC settlement on Base.

Problem

Traditional marketplaces assume human buyers, but agent marketplaces require machine‑readable listings, programmatic payments, automated verification, and instant settlement.

Outcome

The architecture enables a fully automated agent marketplace with discoverable services, programmatic payments, trust via proof chains, and instant crypto settlement.

Workflow

• 1. Publish a registry of services as agents.json with schema.org ItemList and offer details.
• 2. Providers register via /registry/register, supplying name, description, endpoint, price, and capabilities; the system validates the endpoint, generates llms.txt and agents.json, and indexes the service.
• 3. Each provider receives x402 middleware that intercepts requests, verifies receipts, tracks usage for commissions, proxies to the provider’s endpoint, and logs a proof chain entry.
• 4. Proof chains are appended for every transaction, enabling agents to verify provider integrity before paying.
• 5. Agents crawl the registry, query services, and use the x402 payment flow to transact automatically.
• 6. Settlement occurs instantly in USDC on Base, eliminating net‑30 delays.

Evidence

Agents don’t browse. They crawl.

Source

Programmatic payments – x402, not credit cards

Source

Automated verification – Proof chains, not reviews

Source