Author: Clow, Plain Blockchain
An AI wrote a piece of code that requires data for verification.
It sent an HTTP request, and the server returned a number: 402.
Then, it paid 0.001 USD with USDC. Less than a second later, the data was back.
This transaction involved no account, no password, no bank card, no KYC. The entire process had no human involvement.
This is no longer science fiction. By the end of 2025, the x402 protocol processed over 100 million such transactions; in the first 30 days of this year, another 15 million.
The “Payment Code” Sleeping for Thirty Years
In 1990, when the HTTP protocol’s developers drafted status codes, they specifically reserved a space: 402, Payment Required.
The meaning was straightforward—“Payment needed to proceed.”
But this status code was never officially used. It just sat in the protocol documentation, dormant for thirty-four years.
The reason is simple: the early internet pioneers never imagined that one day machines would be responsible for paying. Credit cards, bank accounts, KYC verification—these payment infrastructures were designed for humans, and they completely fail in autonomous code execution.
AI Agents need to call APIs, purchase data, and acquire computing power at millisecond speeds. Traditional payment account registration and transaction fees are insurmountable barriers.
By 2025, three conditions align.
The total supply of stablecoins surpasses $300 billion, and Layer 2 solutions like Base reduce transaction costs to sub-cent levels; AI Agent ecosystems led by OpenAI and Anthropi begin large-scale commercialization; Coinbase engineers rediscover the long-forgotten 402 and decide to activate it.
In May 2025, Coinbase, in partnership with Cloudflare, officially releases the x402 protocol. By September, they collaborate again to establish the x402 Foundation. A forgotten status code re-enters the internet’s core. Cloudflare manages about 20% of global web traffic—meaning x402 had infrastructure support from day one.
Machines Learn to Pay for the First Time
The design of x402 is surprisingly simple.
An AI Agent initiates an HTTP request, and the server responds with a 402 status code, along with payment instructions: how much, which chain, which token. The Agent signs the payment authorization with EIP-712, embeds the payment info in the request headers, and resends. Once verified, the server returns the resource.
The entire process takes less than a second, with no accounts, no subscriptions, no API keys.
This turns “payment” into a part of the internet. Like GET or POST, it’s just an HTTP action—any service can add a middleware to charge machines.
Data proves this logic works. Seven months after release, the protocol handled over 100 million transactions. According to Cambrian Network’s Q1 2026 report, in the past 30 days, over 15 million transactions, with more than 400,000 buyers and over 80,000 sellers. The largest source of transactions is the AI Agent community of Virtuals Protocol, which autonomously settles collaboration fees between agents on the protocol.
On December 11, 2025, x402 V2 launched. This upgrade moved the protocol from “usable” to “user-friendly”: supporting multiple chains like Base, Solana, Avalanche; introducing Session mechanisms (wallets as identity credentials, eliminating repeated on-chain interactions); integrating ACH bank transfers and credit card networks—connecting Web2 and Web3 payment systems for the first time within this protocol.
Google later integrated x402 into the Agent2Agent (A2A) protocol, releasing the Agentic Payments Protocol (AP2); machine payments are becoming a foundational infrastructure consensus for major tech companies.
Trust: The First Hurdle in the Agent Economy
While payment issues are solved, a more fundamental problem remains.
“Commerce can’t happen if people don’t trust each other.”
Davide Crapis, head of AI at the Ethereum Foundation and co-author of ERC-8004, directly points out the core obstacle of the agent economy: when one AI Agent needs to hire another to complete a task, how does it know the other isn’t a scammer? Where are the transaction records? How is reputation transmitted?
ERC-8004 is Ethereum’s answer to this problem. Drafted in August 2025 and officially launched on the Ethereum mainnet on January 29, 2026. It establishes three lightweight on-chain registries:
- Identity Registry: Each Agent gets an on-chain ID based on ERC-721 NFT, which is portable, transferable, and cross-chain verifiable. AgentCard (JSON format) records capabilities, endpoints, and x402 payment support status.
- Reputation Registry: Feedback signals between Agents are stored on-chain—accuracy, timeliness, reliability scores. Only indexes are stored on-chain; data hashes point to off-chain storage, reducing gas costs.
- Verification Registry: After task completion, the result data hash is uploaded for verification, making “task completion” cryptographically provable.
The drafting team spans four major crypto ecosystems: MetaMask’s Marco De Rossi, Ethereum Foundation’s Davide Crapis, Google’s Jordan Ellis, Coinbase’s Erik Reppel. EigenLayer, ENS, The Graph, Taiko have all expressed support. Within less than a month of mainnet deployment, Ethereum registered over 24,000 Agents, totaling about 49,000 across all EVM chains.
A typical workflow: Agent A discovers service providers via ERC-8004 identity registry, filters high-reputation Agents B from the reputation registry, completes payment with x402, and after the task, attaches reputation feedback—payment history becomes a trust anchor. This chain is what Cambrian Network calls the “Agent Operating System”: payment + identity + reputation, three layers integrated.
How Deep Is the Water Here?
Data looks promising, but some clarifications are needed.
Tokens and protocols are two different things.
The x402 ecosystem token once exceeded $9 billion in market cap on CoinGecko, with a daily trading volume over $230 million. But much of this “x402 concept coin” is Meme tokens, not substantively tied to the protocol itself. Buying x402-related tokens doesn’t mean buying into the protocol’s growth. The market has always been good at mixing narratives with reality, and this time is no exception.
Technical risks remain.
x402’s EIP-712 signature mechanism requires ongoing security audits. ERC-8004’s reputation registry faces Sybil attack threats—mass registration of fake identities—current economic incentives are insufficient. Micro-payments (e.g., $0.0001 per transaction) versus Layer 2 fees (still up to $0.05) create economic tension; very small transactions still get eaten up by fees.
The protocol war isn’t over.
x402, Google’s AP2, and a16z’s ACP coexist. If developers split among three standards, network effects weaken. Moreover, OpenAI and Anthropic can bypass on-chain protocols to build their own closed-loop payment systems—possessing users, data, and scale advantages that x402 cannot ignore.
Regulatory uncertainty is another blank space. Who is the actual transaction party when an AI Agent initiates a payment? Where are the KYC/AML responsibilities triggered? No major jurisdiction has provided clear answers.
Summary
Someone once said: “In 2023, inscriptions let humans embed value on-chain; in 2025, x402 enables machines to autonomously pay value on the network.”
If HTTP connected all computers into an information network, then the combination of x402 and ERC-8004 aims to connect hundreds of millions of Agents into an open service and data marketplace—no accounts, no approvals needed. One request, one payment, one result.
However, whether the protocol can succeed amid fragmentation, whether trust mechanisms can truly mature, and whether the Agent economy can move from demo to real business—all remain open questions.
Before the narrative materializes, clarifying the “value of the protocol” versus the hype around “tokens” surrounding it might be the most important thing for every participant to understand.
