HTTP 402 Payment Required is a reserved HTTP status code that indicates payment is required to access a resource. It was reserved for future use in digital payment systems.

x402 is a protocol that implements HTTP 402, enabling pay-before-you-read experiences on the web. The V2 release (December 2025) adds wallet-based identity for reusable sessions, multi-chain support via CAIP standards, and modular architecture for cryptocurrency payments like USDC.

Is x402 V2 backward compatible?

Yes, x402 V2 maintains the core principles of the original protocol while adding advanced features like session reuse and improved multi-chain support.

What is x402? Complete Guide to HTTP 402 and x402 Payment Protocol

What's New in x402 V2

🔐 Wallet-Based Identity

Reusable sessions eliminate re-payment on every call. Reduced latency and lower costs for high-frequency interactions, especially for AI agents.

🔗 Multi-Chain Support

Unified payment interface via CAIP standards. One format works across different blockchains and even legacy payment systems.

⚡ Dynamic Pricing

Automatic API discovery and dynamic payment recipients enable flexible pricing models based on inputs.

🧩 Modular Architecture

Plug-in-driven design separates core protocol from SDK implementation. Cleaner, more extensible, and future-proof.

Why now?

402 stayed "reserved" in the HTTP spec for years. x402 V2 turns it into a production-ready pay-to-unlock experience with wallet identity and multi-chain support.

You will learn

The difference between 402 and 401/403/404
The x402 V2 workflow with sessions
How to finish a one-off payment with USDC

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