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This project is Open Source

Explore the complete collection of h402 solana RPC integration examples in our repository.

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h402 is an open, HTTP-compatible protocol that enables stateless machine-to-machine payments

Thirty-five years after Tim Berners-Lee set aside the 402 Payment Required response code, the web still lacks a native, programmable unit of value. h402 aims to close this gap by providing a thin, header-based payment primitive that integrates directly into any HTTP interaction.

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Overview

h402 repurposes the unused 402 Payment Required HTTP status code to introduce a simple and interoperable payment negotiation mechanism between clients and services. It enables:
  • Machine-to-machine payments using native blockchain assets
  • Service monetization without centralized payment gateways
  • Stateless, cryptographically verifiable interactions
  • Cross-chain and token-agnostic design
Any HTTP-capable agent or service can adopt h402 to define access requirements, request payment and verify them using our protocol.

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Key Capabilities

  • Chain-Plural: The protocol treats multiple settlement networks (EVM chains, Solana and soon many others) as first-class options.
  • HTTP-Native: Seamless integration with existing web infrastructure through standard headers and status codes.
  • Extensible: Support for new payment schemes, compliance requirements, and future network integrations.
  • Production-Ready: Built for real-world deployment with comprehensive tooling and facilitator support.
While clients operate in a completely stateless manner, the Facilitator maintains state for transaction verification and settlement.

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Use Cases

h402 enables a new market layer for code, including:
  • Instant-Settlement Service Calls: LLM inference, real-time market data, per-frame video analytics
  • Compute & Storage Markets: GPU spot markets, elastic storage, DePIN rewards
  • Context & Content on Demand: Per-document legal archives, premium content, scientific datasets
  • Device-to-Device Commerce: EV charging, factory automation, logistics coordination

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Next Steps

This section of the documentation provides everything you need to understand, implement and integrate the h402 protocol: