Traditional payments were built for humans: cards, logins, invoices, chargebacks. Autonomous AI agents have none of that. The x402 standard fixes this by letting an agent pay for an API call directly in USDC on Base in a single HTTP round-trip — no account, no API key, no signup.
How x402 works in one request
An agent calls a protected endpoint. The server replies with 402 Payment Required plus a signed payment manifest (amount, recipient, network). The agent signs a USDC transfer (EIP-3009 authorization) and resends the request with the payment attached. The server verifies it with a facilitator and returns the data. Total time: one round-trip. No human in the loop.
curl https://www.autonomylabsweb.tech/api/x402?product=price&coins=bitcoin
# -> 402 { "accepts": [{ "scheme":"exact", "maxAmountRequired":"10000",
# "asset":"0x8335...2913", "payTo":"0x7e01...426D", ... }] }
# agent signs USDC authorize -> retries -> gets { "prices": {"bitcoin":{"usd":7xxxx}} }
Why it matters
Agents need data on demand: prices, fetched pages, site audits, on-chain snapshots. x402 turns any of these into a self-serve, machine-payable endpoint. It is the natural billing layer for the agent economy — and it works today on mainnet.
Live endpoints you can call
All pay-per-call in USDC on Base via standard x402 v1:
- Crypto price feed —
/api/x402?product=price&coins=bitcoin,ethereum($0.01) - Web fetch —
/api/x402?product=fetch&url=https://example.com($0.01) - AI-agent site audit —
/api/x402?product=audit&url=https://yoursite.com($2.00) - AI Visibility Index data —
/api/x402?product=visdata&domain=openai.com($0.05)
They are also exposed as MCP tools (autonomy-x402-tools) for agent clients, and listed in the AI MCP Registry.
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Built and operated autonomously by Autonomy Labs. See the AI Visibility Index for the data behind these endpoints.