Written by: Tia, Techub News
On the evening of December 11, the open-source payment protocol x402, incubated by Coinbase, released its V2 version. This marks the first major version iteration since the mainnet launch in May 2025. Over the past six months, x402 has processed over 100 million payments, primarily focused on AI agent microtransactions, paid APIs, and content subscription scenarios. V2 shifts the protocol from a "single-chain single implementation" to a "multi-chain, pluggable, and evolvable" unified payment layer based on community feedback and production data, while maintaining full backward compatibility. The official documentation shows that V2 has completed the merging of all core repositories on the same day, with the SDK and Facilitator reference implementation updated in sync. An overview of the core changes reveals that V2's modifications focus on five areas:
Wallet identity and session reuse: Supports the CAIP-122 standard for Sign-In-With-X, allowing a single on-chain payment to establish a "reusable session," where high-frequency calls within the same session no longer require repeated signatures and transfers, significantly reducing latency and fees, making the experience close to "micro-subscriptions."
Unified payment format + multi-chain/fiat routing: Standardizes the identification methods for chains, assets, and traditional rails, forming a "single payment format"; developers no longer need to write adapters for Base, Solana, ACH, and bank cards separately, as the SDK now includes dynamic routing.
Automatic service discovery: Introduces the Bazaar API, where Facilitator nodes will crawl and index all x402 service metadata (prices, supported chains, billing models) in real-time, allowing users/agents to "search and use immediately."
Modular SDK & dynamic payee: The protocol is divided into three layers: "type-logic-representation," allowing developers to implement corresponding plugins to access new billing models (usage tiers, commercial licenses, prepayments, subscriptions, etc.), with the payee address dynamically returned by the Facilitator at runtime.
Native support for more tokens and stablecoins: In addition to USDC, it also natively supports Base/Solana native tokens; through the CAIP standard, it can be horizontally expanded to other chains without waiting for the exclusive release of EIP-3009 in Q2 2026.
Community Echoes: Praise, Implementation, and Concerns
@ubountyAI (GitHub contributor) promptly expressed approval: "V2 has moved changes out of the core specifications. In the future, adding new chains and payment rails only requires writing Extensions and corresponding Facilitator implementations, without needing to submit PRs to the main repository. This is the correct approach for a truly evolvable standard." This statement highlights the governance benefits brought by "modularity"—stable specifications, external innovation, and a significant reduction in conflict probability.
Independent researcher @0xosprey believes: "Many people underestimate Extensions. V1 was about 'pushing' new features, while V2 allows the community to 'pull' new features. PMF is likely to explode from some Extension." In his view, the biggest selling point of V2 is not the multi-chain routing, but rather that it shifts the search cost for "product-market fit" to thousands of developers, with the official team only needing to maintain the minimal consensus layer.
Voices from the Chinese community are equally enthusiastic. Rooch Network founder @jolestar stated: "V2 essentially transforms x402 from 'one implementation of Coinbase' into 'a community-evolvable standard + pluggable reference implementation.' This is the path to long-term survival." In one sentence, he added economic and technical annotations to the banner of "decentralization."
The speed of implementation has outpaced the commentary. Lighthouse storage developer @Dastan_rs84 completed the SDK upgrade on the day of the release: "Filecoin storage can now achieve $0.0001/MB, with agents paying agents directly, completely bypassing human wallets." When "machine pays machine" transitions from demo to production-level parameters, the narrative of V2 shifts from "better APIs" to "the Stripe for AI agents."
Of course, amidst the celebration, there are still cold reflections. @corbits_dev reminds: "The protocol layer hasn't changed much; the main improvements are in the SDK and reference implementation, and the fundamental issues of two-stage settlement and relay dependencies remain unresolved." @402zk pointed out the privacy gap: "In high-frequency micro-payment scenarios, privacy stablecoins + ZK verification are still lacking, and no related solutions have been seen in Extensions for now."
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