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For decades, the HTTP 402 Payment Required status code sat unused, a placeholder for the internet’s missing native payment layer. b402 activates it, extending its semantics into a programmable settlement layer for agents on the BNB Chain.

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What is HTTP 402?

HTTP 402 is a standard, though rarely implemented, HTTP response code indicating that payment is required to access a resource. In b402, this code becomes a living bridge between the web and on-chain payments. When a client (human or agent) requests a resource:
  • The server responds with 402 Payment Required if payment or identity verification is needed.
  • The response includes structured payment instructions — such as amount, token, and destination address.
  • The client can then complete the payment or verification programmatically, without accounts or intermediaries.

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Why b402 Uses HTTP 402

b402 redefines HTTP 402 as the missing primitive for agent-to-service commerce. It enables frictionless, verifiable payments directly over HTTP for:
  • Machine-to-machine (M2M) interactions, such as AI agents and automated scripts.
  • Usage-based access, including APIs, compute units, or paywalled data.
  • Microtransactions settled instantly on-chain with BNB or supported tokens.
  • Identity-gated requests, verified through ERC-8004 identities.
By embedding payment and verification directly within the HTTP layer, b402 keeps the protocol web-native, crypto-secure, and developer-friendly.