Author: Tia, Techub News
On the evening of December 11th, x402, an open-source payment protocol incubated by Coinbase, released version V2. This is the first major version iteration since its mainnet launch in May 2025. In the past six months, x402 has processed over 100 million payments, primarily concentrated in AI-assisted microtransactions, paid APIs, and content subscription scenarios. Based on community feedback and production data, V2 transforms the protocol from a "single-chain, single-implementation" approach to a unified payment layer that is "multi-chain, pluggable, and evolvable," while maintaining full backward compatibility. Official documentation shows that V2 completed the merging of all core repositories on the same day, and the SDK and Facilitator reference implementation were updated simultaneously.
... Key Changes at a Glance: V2's changes are concentrated in five areas: Wallet Identity and Session Reuse: Supports CAIP-122 standard Sign-In-With-X, allowing for the establishment of a "reusable session" with a single on-chain payment. High-frequency calls within the same session no longer require repeated signing and transfers, significantly reducing latency and fees, providing an experience close to "micro-subscription." Unified Payment Format + Multi-Chain/Fiat Currency Routing: Standardizes the identification methods for chains, assets, and traditional tracks, forming a "single payment format." Developers no longer need to write separate adapters for Base, Solana, ACH, and bank cards; the SDK has built-in dynamic routing. Automatic Service Discovery: A new Bazaar API has been added. Facilitator nodes will crawl and index the metadata (price, support chain, billing mode) of all x402 services in real time, allowing users/agents to "search and use immediately". Modular SDK & Dynamic Payment Provider: The protocol is broken down into three layers: "type-logic-representation". Developers only need to implement the corresponding plugins to access new billing modes (tiered usage, commercial licensing, prepaid, subscription, etc.). The payment address can also be dynamically returned by Facilitator at runtime. Native support for more tokens and stablecoins: In addition to USDC, it is also compatible with Base/Solana native tokens by default; it can be horizontally extended to other chains through the CAIP standard without waiting for the exclusivity of EIP-3009 to be lifted in Q2 2026. Community feedback: Praise, implementation, and concerns. @ubountyAI (GitHub contributor) immediately gave positive feedback: "V2 has moved the changes out of the core specification. In the future, adding new chains and new payment tracks only requires writing Extensions and corresponding Facilitator implementations, without having to submit them to the main repository." "PR. This is the right way to create a truly evolvable standard." This single sentence highlights the governance benefits of "modularization"—stable standards, externalized innovation, and a sharp decrease in the probability of conflict. Independent researcher @0xosprey believes: "Many people underestimate Extensions. V1 was about 'pushing' new features, while V2 is about letting the community 'pull' new features. PMF is likely to explode starting with a certain Extension." In his view, V2's biggest selling point is not multi-link routing, but rather shifting the search cost of "product-market matching" to thousands of developers, with the official team only needing to maintain a minimal consensus layer. The Chinese community's voice is equally enthusiastic. Rooch Network founder @jolestar believes: "V2 essentially transforms x402 from 'a Coinbase implementation' into 'a community-evolvable standard + a pluggable reference implementation.'" This is the path to long-term survival.” In short, it provides a dual economic and technological footnote to the banner of “decentralization.” The speed of implementation is faster than the comments. Lighthouse storage developer @Dastan_rs84 completed the SDK upgrade on the day of release: “Filecoin storage can now achieve $0.0001/MB, with agents paying agents directly, completely bypassing human wallets.” When “machine paying machine” moves from demo to production-grade parameters, the V2 narrative is no longer about “a better API,” but rather “AI-agent Stripe.” Of course, beyond the celebration, there are still sobering reflections. @corbits_dev pointed out: "The protocol layer hasn't changed much; it's mainly about improving the SDK and reference implementation. The fundamental issues of two-phase settlement and relay dependencies haven't been resolved." @402zk further pointed to the privacy gap: "In high-frequency micropayment scenarios, privacy-preserving stablecoins + ZK verification are still lacking; I haven't seen any relevant solutions in the Extensions yet."