HTTP 402 resurrected after being sealed for 28 years: can the x402 protocol support the payment future of AI Agents?

An HTTP status code that has been dormant for almost thirty years has recently come back to life.

In 1997, a 402 status code was reserved in the HTTP protocol, meaning “Payment Required”. However, at that time, online payment had not yet become mainstream, so this code has been sitting there collecting dust.

The situation has changed now. Stablecoins have matured, L2 has reduced the transfer fees, and more importantly—AI Agents have started to run all over the world, and they need to pay for services themselves.

A leading exchange seized this opportunity and unearthed this old relic, creating the x402 protocol. The core logic is very straightforward: when AI or humans access paid content, there is no need to register, no need to jump pages, just pay directly on the chain.

Sounds simple? Behind it is a whole ecosystem being rebuilt. From protocol standards to infrastructure, and then to applications, x402 is attempting to rewrite the payment rules of the internet.

This article will break down what protocols, chains, infrastructure, and applications are actually running, aside from those flying Meme coins.

Protocol Layer: Equip AI with a Wallet

x402 is not a single protocol, but rather a set of modular combinations aimed at solving three problems: how AI communicates with each other, how to make payments, and how to establish trust.

The core of course is the x402 protocol itself. It is designed based on HTTP 402, and when AI accesses paid APIs or content, it will automatically receive a payment request and then complete the on-chain transfer using stablecoins like USDC. The entire process? No registration, no redirection.

In order to enable collaboration between AIs, Google proposed the A2A protocol (Agent-to-Agent) to standardize communication and task handover between agents. Anthropic also introduced the MCP protocol, which provides AIs with access tools and interfaces for contextual data.

Based on MCP, Google has released a new AP2 Payment Protocol, allowing AI Agents to call services on demand and make automatic payments, while being compatible with traditional payments and x402.

These protocols can be implemented, and the key relies on Ethereum's EIP-3009 extension. It allows users to authorize token transfers through signatures without paying Gas fees—this solves the longstanding problem of “What to do if there's no ETH in the AI wallet?”

Also in progress is ERC-8004, which establishes an on-chain identity and reputation system for AI Agents, recording execution records and trust scores, allowing service providers to determine the reliability of the agent.

In simple terms, the x402 protocol layer is building a “language + currency + trust” system for AI services. This allows AI to complete transactions, collaborate, and make payments on its own without anyone watching. This is the first step for the entire ecosystem to be able to operate.

Infrastructure Layer: Making Payments Truly Work

The agreement defines the rules of the game, but what truly makes it operate is a complete set of infrastructure.

First, we have to mention Cloudflare. It, along with a leading exchange, initiated the x402 Foundation, integrating the protocol into its own CDN nodes and development tools. Cloudflare not only provides a global distribution network but also supports a “pay-per-use” delayed payment mechanism - AI first retrieves the content, and the settlement occurs later.

Next is x402 Facilitator, which is a payment aggregator. It is responsible for helping AI complete the entire on-chain process of “payment, settlement, broadcasting”. Users or AI only need to initiate an HTTP 402 request, and the Facilitator will pay the Gas, package the transaction, and complete the on-chain broadcasting. The settlement uses the EIP-3009 standard, allowing for a one-time authorization of USDC deductions. Throughout the process, the AI does not need to hold tokens or manually sign.

According to the data, a leading exchange remains the largest Facilitator, processing over 1.35 million transactions and covering 80,000 buyers. PayAI ranks second, being quite active on chains like Solana and Base, with a cumulative transaction volume of $280,000, and even surpassing a leading exchange in the number of users. Others like X402rs, Thirdweb, and Open X402 are also competing for market share.

In addition to the Facilitator, a “native settlement blockchain” specifically designed for x402 has emerged. The representative project is Kite AI, which is one of the first Layer 1s to fully embed the x402 payment primitives into the underlying layer, having already received investments from prominent institutions like Ventures and PayPal Ventures. It does not directly handle payment verification, but instead provides an execution and settlement environment for x402 transactions, supporting agents to automatically initiate, receive, and reconcile on-chain payments through standardized authorization instructions.

At the execution layer, in addition to Kite AI, Peaq in the DePIN field is also making strides. This is a public chain focused on the machine economy, and it natively supports the x402 protocol, enabling automatic payment and settlement between devices and agents.

The representative project of the x402 collaboration layer is Questflow, where developers can publish agency tasks, set prices, and directly complete on-chain settlements through x402. It has already collaborated with platforms such as Virtuals and Gate.

In addition, AurraCloud and Meridian provide multi-chain settlement and custody services for the x402 protocol.

Overall, the infrastructure layer of x402 is being built around three core issues: how to send out requests, how to receive payments securely, and how to quickly implement them across different chains. This determines whether the entire payment system can truly operate.

Application Layer: Who is really using x402?

The protocol is set up, and the infrastructure is in place, but there hasn't been much movement at the application layer. There are very few projects implemented.

• Daydreams: Creating an LLM inference platform using x402 for payment.
• Heurist Deep Research: A Web3 native AI research platform where users pay per query using USDC, automatically generating multi-page research reports.
• Gloria AI: Achieve pay-per-use news with x402.
• Snack Money API: A micropayment interface for platforms like X, Farcaster, focusing on small payments and tipping around identity and social interactions.
• tip.md: Allow the AI assistant to directly help users complete cryptocurrency tips in the chat interface, with USDC tips going through the complete payment process via MCP+x402.
• Firecrawl: A web scraping and cleaning API that converts websites into data usable by LLMs, with pay-per-call via x402.

Overall, the application layer of x402 is still in exploration. The functional platform is just starting, and the scale effect has not yet formed. It depends on who can first create a truly usable, payable, and reusable product.

Meme: Prices and popularity are soaring

With the rise of the x402 concept, the market quickly saw the emergence of a batch of “narrative-hitching” native Meme projects. The most representative is PING, which was issued on the Base chain and directly surpassed a market value of ten million dollars on the day of its launch.

In addition to PING, other tokens such as “PENG” and “x402” have emerged in the community. These Meme coins do not currently form the core of the protocol, but they can provide attention, popularity, and early liquidity.

What obstacles does x402 face on the ground?

The concept of x402 is quite eye-catching, but to truly implement it, there are still several hurdles to overcome.

First, there is a lack of truly usable products. Currently, most projects are still in the testnet and proof-of-concept stages, with a rough user experience.

Second, the technology stack is complex, and integration costs are high. x402 involves a new protocol that integrates multiple modules such as payment, signed transfers, and proxy communication, which poses a significant barrier to entry for developers.

Third, compliance risk. The focus on “no accounts, no redirect payments” improves efficiency, but it bypasses the KYC/AML requirements of traditional payment systems, which may pose regulatory risks in certain regions.

Fourth, the network effects have not yet formed. The core of the payment protocol lies in ecological synergy, but currently there are not many services and platforms connected to x402, and the ecosystem has not yet formed a self-sustaining cycle.

In summary, x402 is still some distance from “mass adoption”. There are several hurdles to overcome from technology to real-world implementation.

Where are the participation opportunities?

From the perspective of participation, x402's long-term opportunities are more in the layout of infrastructure and key platforms.

First, there are the foundational chains and infrastructure. x402 core relies on Ethereum ecosystem standards such as EIP-3009 and ERC-8004, while Base is currently the most prominent landing chain, with a strong stablecoin closed loop and a developer-friendly environment, expected to be the first to incubate leading products. Solana also has advantages in high-frequency payments, suitable for Agent micro-transaction scenarios.

Secondly, there is the native settlement blockchain, such as Kite AI, as well as payment aggregators and service platforms like PayAI, Meridian, and AurraCloud. They are responsible for verifying payments, bearing Gas, and interfacing with APIs. Once a universal entry point is formed, the value will rapidly amplify.

As for the token side? It's better to be cautious. Currently, the tokens related to x402 are small in size and highly volatile, and many Meme coins are still in the narrative-driven stage. Projects that truly have payment application or platform utility value are more worth paying attention to.

What do insiders think?

In the current situation where market voices are diversified, the views of some leading Builders and KOLs on the x402 ecosystem are also worth considering.

Haotian pointed out that the current x402 craze is largely driven by Meme hype, and the real “main course”—the implementation of technology and the formation of ecosystems—has not yet begun. Only through market selection will quality projects emerge. He believes that viewing x402 as a short-term speculation misreads the logic and rhythm of the entire track.

Laobai points out from a historical perspective that micropayments are not a new concept. From early Bitcoin and the Lightning Network to Nano, IOTA, and BSV, the crypto space has made several attempts to promote small transaction applications, but has consistently struggled to achieve large-scale implementation. The difference with x402 is that it has, for the first time, identified the true “subject” that needs micropayments: AI Agent, rather than human users.

Danny raised the perspective higher and pointed out that the greater potential behind x402 is the payment infrastructure of the “machine economy”. From on-chain knowledge collaboration, API economy to AI-driven DAO governance, all these M2M (machine-to-machine) transaction demands inherently require a frictionless, account-free, and automatically executable payment layer.

Blue Fox Notes starts from the architectural level, believing that Facilitator, as a key link in payment verification and execution, is becoming one of the core infrastructures in the track. Projects like PayAI, a leading exchange, and Pieverse have already formed a distinct competitive landscape.

Finally, Zhixiong Pan raised a long-term perspective question: Can an agent truly “hold cryptocurrency and pay”? This involves key mechanisms such as private key custody and permission management.

Overall, x402 may currently have fluctuations in popularity, but in the eyes of long-term believers, it has just entered a true construction period.