Learn by doing

Build your first x402 payment loop.

x402 Academy is the tutorial companion to the official x402 documentation. Start with the 402 challenge, then build seller routes, buyer agents, facilitator mental models, and checkpoint projects that prove the integration works.

Start quickstart Open free tools Open x402 docs

Protocol board

1. GET /paid-resource
2. 402 + payment requirements
3. signed payment payload
4. verify + settle
5. 200 OK + paid content

The whole course keeps returning to this loop. The official docs own the exact SDK surface; this site teaches how to think, test, and ship around it.

Free tools

Practice the flow before you wire a wallet.

Phase 2 adds browser-only teaching tools: a flow simulator, a stack-specific quickstart configurator, and a scheme quiz with reread recommendations.

how does x402 work

x402 Flow Simulator

Step through a full x402 exchange from the first unpaid request through the 402 challenge, signed retry, verification, settlement, and final 200 response.

x402 quickstart

x402 Quickstart Configurator

Pick a framework and network to generate a tailored, copy-paste x402 seller quickstart sequence with explanatory notes.

learn x402

Payment Scheme Quiz

Check your understanding of x402 roles, headers, schemes, networks, facilitator responsibilities, and retry safety.

Course map

Follow the learning path in order.

The concept is deliberately split by role. Sellers enforce payment requirements. Buyer agents discover and pay. Facilitators simplify verification and settlement. Projects make the pieces real.

01 Quickstart See the 402 challenge, payment retry, and successful response as one mental model. 02 Seller track Add x402 payment requirements to an API route and test the unpaid and paid paths. 03 Buyer agent track Wrap a client so it can discover requirements, sign a payload, and retry automatically. 04 Facilitator track Understand verification, settlement, duplicate settlement protection, and production boundaries. 05 Projects Build small checkpoints that prove your x402 integration works end to end.

What this site teaches

x402 is not a checkout page. It is an HTTP-native handshake: a client asks for a resource, the server replies with payment requirements, the client attaches a signed payment payload, and the server returns the resource after verification and settlement. That makes it especially useful for paid APIs, paid content, and agents that need to pay per request without creating accounts first.

This academy stays in tutorial mode. When you need exhaustive field definitions, current SDK signatures, or network-specific production rules, use docs.x402.org as the reference source.

"The 402 (Payment Required) status code is reserved for future use."
Primary source: RFC 9110, section 15.5.3

x402 gives that reserved status code an implementation pattern for programmatic payments. The Linux Foundation page also documents that the x402 project was contributed by Coinbase and established as a Linux Foundation Projects series.

Where to go next

If you already know the basic HTTP flow, jump to the seller track. If you are building autonomous clients, start with the buyer agent track. If you need to explain verification and settlement to a teammate, read the facilitator track before you wire production traffic.

Sources used

  1. x402 docs: Introduction

    Defines x402 as an open payment standard for charging APIs and content directly over HTTP.

  2. x402 Foundation GitHub repository

    Open-source SDKs, examples, and the typical x402 request/payment/settlement flow.

  3. RFC 9110: HTTP Semantics, section 15.5.3

    The HTTP specification reserves status code 402 for future use.

  4. Linux Foundation: x402 Foundation

    Governance note that the project was contributed by Coinbase and established as an LF Projects series.

  5. agenteconomy.to data

    Public agent-payment dashboard with x402 transaction and volume totals, updated July 6, 2026.