CrawlerToll

x402

x402 is the Coinbase-launched, now-Linux-Foundation-governed agent-payment standard. It defines a payment protocol that rides natively on HTTP 402 — agents sign authorizations with their wallet, retry the request with the signed authorisation in a payment header, and the payment is verified and settled by a facilitator.

Which x402 version

The CrawlerToll unlock service speaks x402 V2, where the agent sends the signed authorisation in a PAYMENT-SIGNATURE header. It also accepts V1, which uses X-PAYMENT.

If you build an AI agent that pays for sealed articles, follow AI agents.

How CrawlerToll uses it

x402 is the rail AI agents use to pay for a sealed article, in USDC straight to the publisher's own wallet.

  1. The agent asks the unlock service for an article's key. With no payment attached, the service answers 402 with an offer, signed with the service's published key.
  2. The agent's wallet signs an exact-scheme USDC transfer authorisation for the amount in the offer, and the agent retries with it in the PAYMENT-SIGNATURE header. @crawlertoll/sdk does both steps for you, within a spending cap you set.
  3. The unlock service checks the payment, has a facilitator settle it on-chain to the publisher's wallet, and only then returns the content key.

Charthouse never holds the money, a facilitator API key or a wallet key. Settlement runs through a keyless third-party facilitator; a publisher can choose their own. See settlement rails.

Supported networks

| Network | USDC contract | |---|---| | Base | 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 | | Base Sepolia (test) | 0x036CbD53842c5426634e7929541eC2318f3dCF7e |

The Base Sepolia network uses free test USDC, so you can practise an agent before spending real money.

See also