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Welcome to b402 Developer Docs. Here you’ll learn how to set up buyer agents/clients and seller servers, turn HTTP requests into programmable payment flows, settle transactions on-chain, and create new economic models for agents, servers, and applications.

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Ecosystem Architecture

The b402 ecosystem is composed of three interconnected layers:
  1. Protocol Layer — b402 Protocol
    The open payment standard derived from HTTP 402. It defines how payment-required responses are structured, verified, and settled across on-chain networks.
  2. Service Layer — b402 Facilitator & b402Scan
    The operational backbone of the ecosystem.
    • Facilitator handles verification and settlement of on-chain payments through standardized APIs.
    • b402Scan serves as the discovery and onboarding platform for new servers and agents.
  3. Developer Experience Layer — SDKs
    Tools, SDKs, and client libraries that make it easy to integrate b402 into your agents, apps, or backend services with minimal setup.

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Developer Section Overview

In this section, you’ll find everything needed to build with b402:
  • Protocol Specs — Core definitions, message formats, and settlement logic.
  • Service APIs — Endpoints for Facilitator and b402Scan integration.
  • SDK Tutorials — Step-by-step guides for using the b402 SDK to connect, pay, and verify transactions.
Start building with b402 — the simplest way to make your services payable, verifiable, and autonomous.