x402 Guides (5 published)

AgentIndex publishes 5 long-form guides for builders working with the x402 payment protocol. The directory pages show which services accept x402 payments; the guides explain the protocol itself — where the HTTP 402 status code came from, how a paid request moves from challenge to settlement, and how to price an API that autonomous agents can pay for without accounts or API keys.

Every guide is written against the live directory dataset and links straight into it: category hubs, chain hubs, facilitator profiles, and price-band pages. The questions at the end of each guide are answered in plain language and marked up as structured data, so readers and answer engines get the same facts. New guides join the collection with the dataset refresh cycle, and each guide's Related box points to the directory pages that back its claims.

• What Is x402 Protocol? Open Payments for AI Agents

  x402 is an open payment protocol originated by Coinbase that activates HTTP 402 for stablecoin micropayments. Definition, origins, and ecosystem data.

• How Does x402 Work? The Payment Flow, Step by Step

  Step-by-step walkthrough of the x402 payment flow: the 402 challenge, the signed USDC payment, facilitator verification and settlement, and fulfillment.

• Monetize AI Agent API: Per-Request Pricing with x402

  How to charge AI agents per API call with x402: per-request pricing from 100 live services, chain and facilitator choices, and realistic price points.

• HTTP 402 Explained: The Status Code That Charges You

  HTTP 402 Payment Required sat reserved in the spec for decades. Read the status code's history, why nothing ever used it, and how x402 finally puts it to work.

• What Is a Payment Facilitator in x402?

  In x402, a payment facilitator verifies signed payments and settles them on-chain so servers skip running nodes. The role explained, plus the landscape.