Written by: Clow
An AI wrote a piece of code that needed data for validation.
It made an HTTP request, and the server returned a number: 402.
Then it paid 0.001 dollars in USDC. In less than a second, the data came back.
This transaction had no account, no password, no bank card, and no KYC. The whole process had no human involvement.
This is no longer science fiction. By the end of 2025, the x402 protocol had handled over 100 million such transactions; in the first 30 days of this year alone, there were an additional 15 million.
01 The “Payment Code” That Has Slept for Thirty Years
In 1990, the drafters of the HTTP protocol specifically left a placeholder for a status code: 402, Payment Required.
The meaning is very straightforward — "Payment is needed to proceed."
But this status code has never been officially used. It has remained dormant in the protocol documentation for thirty-four years.
The reason is not complicated: the early builders of the internet never imagined that one day machines would be making payments. Credit cards, bank accounts, KYC verification—these payment infrastructures were designed for humans and completely fail in front of autonomously running code. AI Agents need to call APIs, purchase data, and obtain computing power at millisecond speed, and the account registration and transaction fee thresholds of traditional payments become insurmountable barriers.
By 2025, three conditions were simultaneously met.
The total supply of stablecoins exceeded 300 billion dollars, with L2s represented by Base driving the cost of a single transaction down to the sub-cent level; the AI Agent ecosystem, led by OpenAI and Anthropic, began large-scale commercialization; engineers at Coinbase unearthed that long-forgotten 402 and decided to activate it.
In May 2025, Coinbase officially released the x402 protocol in partnership with Cloudflare. In September, they announced the establishment of the x402 Foundation together. A forgotten status code returned to the center of the internet. Cloudflare manages about 20% of global web traffic — this means x402 had no shortage of infrastructure access from day one.
02 Machines, for the First Time, Learned to Pay
The design of x402 is surprisingly simple.
The AI Agent initiates an HTTP request, the server returns a 402 status code, and simultaneously attaches a payment request: how much, which chain, which token. The Agent authorizes it with an EIP-712 encrypted signature, sends the payment information in the request header again, and the server, after verification, returns the resource.
The whole process takes less than a second, without an account, subscription, or API Key.
This turned "payment" into a part of the internet. Like GET and POST, it is just an HTTP action, and any service can charge machines with just a line of middleware.
Data proves that this logic is viable. About seven months after the protocol was released, it processed over 100 million transactions. According to the Cambrian Network Q1 2026 report, in the past 30 days there were over 15 million transactions, with buyers exceeding 400,000 and sellers surpassing 80,000. The AI Agent community of Virtuals Protocol is the largest single source of transactions, autonomously settling collaboration fees between Agents on the protocol.
On December 11, 2025, x402 V2 went live. This upgrade advanced the protocol from "usable" to "user-friendly": supporting multi-chain parallelism including Base, Solana, and Avalanche, introducing a session mechanism (where wallets serve as identity credentials, eliminating the need for on-chain interaction on repeat visits), and bridging ACH bank transfers with credit card networks — the payment systems of Web2 and Web3 were for the first time connected within this protocol.
Subsequently, Google integrated x402 into the Agent2Agent (A2A) protocol and released the Agentic Payments Protocol (AP2); machine payments are becoming a consensus among large tech companies' infrastructures.
03 Trust Is the First Hurdle for the Agent Economy
With the payment issue resolved, there remains a more fundamental question unanswered.
"Commerce can't happen if people don't trust each other."
Davide Crapis, AI lead at the Ethereum Foundation and one of the co-drafters of ERC-8004, pinpointed the core obstacle of the agent economy: when an AI Agent needs to hire another Agent for a task, how does it know the other isn't a scammer? Where are the transaction records? How is reputation transferred?
ERC-8004 is Ethereum's answer to this issue. The draft was made in August 2025 and officially launched on the Ethereum mainnet on January 29, 2026. It established three lightweight registries on-chain:
Identity Registry: each Agent receives an on-chain ID based on the ERC-721 NFT, portable and transferable, cross-chain traceable, with AgentCard (in JSON format) recording capabilities, endpoints, and x402 payment support status;
Reputation Registry: feedback signals between Agents are archived on-chain — accuracy, timeliness, and reliability scores, with only indexes retained on-chain, and data hashes pointing to off-chain storage, reducing gas costs;
Verification Registry: after task completion, result data hashes are requested for verification on-chain, giving "whether the task was genuinely completed" cryptographic verifiability.
The drafting team spans four major crypto ecosystems: Marco De Rossi from MetaMask, Davide Crapis from the Ethereum Foundation, Jordan Ellis from Google, and Erik Reppel from Coinbase. EigenLayer, ENS, The Graph, and Taiko have all expressed support. Less than a month after launching on the mainnet, the number of registered Agents on Ethereum surpassed 24,000, with approximately 49,000 across all EVM chains.
A typical workflow looks like this: Agent A discovers a service provider through the ERC-8004 Identity Registry, filters the Reputation Registry to select a high-scoring Agent B, pays via x402, and after the task is completed, attaches the payment record with reputation feedback — the payment history becomes a credit anchor. This connection is what Cambrian Network refers to as the "Agent Economy Operating System": payment + identity + reputation, merging three layers into one.
04 How Deep Is the Water Here?
The data looks good, but there are a few things to clarify.
Tokens and protocols are two different things.
The market capitalization of the x402 ecosystem token once exceeded 9 billion dollars on CoinGecko, with daily trading volume exceeding 230 million dollars. However, a large number of "x402 concept coins" are Meme tokens, which have no substantial binding to the protocol itself. Buying x402-related tokens does not equate to buying into the growth of the x402 protocol. This market has always excelled at mixing narrative with reality, and this time is no exception.
Technical risks have not been resolved.
The EIP-712 signing mechanism of x402 requires continuous security audits. The ERC-8004 Reputation Registry faces the threat of Sybil attacks — bulk registration of false identities, and existing economic incentive mechanisms are still not well-defined. The economic tension between high-frequency micropayments (at $0.0001 each) and L2 fees (still reaching $0.05) means very small transactions could be eaten up by fees at this stage.
The protocol war is not over.
x402, Google’s AP2, and a16z's ACP all coexist. If developers split among these three standards, the network effects will significantly diminish. Additionally, OpenAI and Anthropic can completely bypass on-chain protocols and build their own closed-loop payment systems — they have users, data, and scale advantages, which present competitive pressure that x402 cannot ignore.
On the regulatory front, there is another blank. For a payment initiated autonomously by an AI Agent, who is the transactional entity? Where is the trigger point for KYC/AML responsibility? No major jurisdiction has provided a definitive answer.
05 Conclusion
Someone once wrote a line that is fitting to quote here: "The inscriptions of 2023 allowed humans to engrave value on the chain; the x402 of 2025 allows machines to autonomously pay value on the network for the first time."
If HTTP connected computers worldwide into an information network, the combination of x402 and ERC-8004 attempts to connect billions of Agents into an open service and data market — no account needed, no approval required, one request, one payment, one result.
However, whether the protocol can win amid fragmented competition, whether the trust mechanism can truly be perfected, and whether the Agent economy can transition from demo to real business… these remain unresolved issues.
Before narratives take root, distinguishing "the value of the protocol" from "the tokens hyped around the protocol" may be the most important thing for every participant to clarify.
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