x402 V2 Protocol Upgrade: Multi-Chain Routing and AI-Native Payments Across Base, Solana and Traditional Rails

Source: Cryptonews Original Title: Coinbase-backed x402 V2 links Base, Solana and cards for AI-native payments Original Link:

Protocol Overview

The x402 payments protocol, incubated by a leading platform for autonomous machine-to-machine transactions, released its V2 upgrade on December 11, 2025. The protocol has processed more than 100 million payments across APIs, AI agents, and web services since its initial deployment six months prior.

Key Enhancements

Multi-Chain and Multi-Asset Standardization

V2 standardizes network and asset identification, enabling a single payment format to operate across multiple blockchains, including Base and Solana, as well as traditional payment systems such as ACH and card networks. This design positions x402 as a unified payment layer for cryptocurrency and legacy financial infrastructures.

Wallet-Based Sessions

The upgrade introduces wallet-based sessions that enable subscription-style access and repeated use of purchased resources without restarting the payment flow. This feature is designed to reduce overhead for high-frequency workloads such as large language model inference, automated API calls, and autonomous agent operations by eliminating unnecessary on-chain interactions. Sessions are tied to wallet ownership rather than API keys.

Modular Architecture

The upgrade establishes a separation between clients, servers, and facilitators, allowing developers to add new blockchains, assets, and payment schemes as isolated modules without modifying the protocol’s foundation. Reference software development kits have been rewritten with a plug-in driven architecture based on feedback from early adopters.

Service Discovery

A new Discovery extension allows x402-enabled services to expose metadata that facilitators can crawl and index, enabling AI agents to automatically discover services, understand pricing, and initiate payments.

Technical Details

The protocol utilizes the HTTP 402: Payment Required status code as a payment mechanism. Transactions typically settle using stablecoins on Layer 2 networks such as Base. An open standards foundation established in September 2025 includes major technology and financial services companies among its members supporting protocol development.