When AI begins to pay for itself

The dormant “payment code” after thirty years

Article by: Clow, Plain Blockchain

An AI wrote a piece of code that requires data to verify.

It sent an HTTP request, and the server returned a number: 402.

Then, it paid $0.001 in 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 handled over 100 million such transactions; in the first 30 days of this year, another 15 million.

The dormant “payment code” after thirty years

In 1990, the draft creators of the HTTP protocol specifically reserved a status code: 402, Payment Required.

The meaning was straightforward—“Payment needed to access.”

But this status code was never officially used. It just sat in the protocol documentation, sleeping for thirty-four years.

The reason is simple: the pioneers 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 they completely fail in autonomous code execution.

AI agents need to call APIs, purchase data, and acquire computing power at millisecond speeds. Traditional payment registration and transaction fees are insurmountable barriers.

By 2025, three conditions will be met simultaneously.

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 unearth the long-forgotten 402 status code and decide to activate it.

In May 2025, Coinbase, in partnership with Cloudflare, officially released the x402 protocol. By September, they announced the formation of the x402 Foundation together. A forgotten status code reenters the center of the internet. Cloudflare manages about 20% of global web traffic—meaning x402 had infrastructure support from day one.

Machines, for the first time, learned to pay

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 info with EIP-712 encryption, embeds it 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 the protocol’s release, it processed over 100 million transactions. According to Cambrian Network’s Q1 2026 report, in the past 30 days, over 15 million transactions occurred, with more than 400,000 buyers and over 80,000 sellers. The largest source of transactions is the AI agent groups of Virtuals Protocol, autonomously settling collaboration fees among 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 a Session mechanism (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 is the first hurdle in the agent economy

The payment problem is solved, but a more fundamental issue remains.

“Commerce can’t happen if people don’t trust each other.”

Davide Crapis, head of AI at the Ethereum Foundation and co-drafter of ERC-8004, directly pointed 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, 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 submitted on-chain for verification, making “task completion” cryptographically provable.

The drafting team spans four major crypto ecosystems: Marco De Rossi of MetaMask, Davide Crapis of Ethereum Foundation, Jordan Ellis of Google, Erik Reppel of Coinbase. EigenLayer, ENS, The Graph, Taiko have all expressed support. Within less than a month of mainnet deployment, over 24,000 agents registered on Ethereum, totaling about 49,000 across all EVM chains.

A typical workflow is as follows: Agent A discovers service providers via ERC-8004 identity registry, filters by reputation registry to select high-scoring Agent B, completes payment with x402, and after the task, attaches payment records as reputation feedback—payment history becomes a trust anchor. This chain is what Cambrian Network calls the “agent economic operating system”: payment + identity + reputation, three layers integrated.

How deep is the water here?

Data looks promising, but a few things need clarification.

Tokens and protocols are not the same.

The x402 ecosystem token once exceeded a market cap of $9 billion on CoinGecko, with a daily trading volume over $230 million. But many “x402 concept tokens” are meme tokens, not substantively linked 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 different.

Technical risks remain unresolved.

x402’s EIP-712 signature mechanism requires ongoing security audits. ERC-8004’s reputation registry faces threats of Sybil attacks—mass registration of fake identities—current economic incentives are not fully robust. Micro-payments (per transaction $0.0001) versus Layer 2 fees (still up to $0.05) create economic tension; very small transactions still get eaten up by fees.

The protocol war is not 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—they have users, data, and scale advantages that x402 cannot ignore.

Regulatory issues remain a blank space. Who is the actual transaction party in an AI agent-initiated payment? Where is the trigger point for KYC/AML responsibilities? 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 for the first time.”

If HTTP connected global 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 “tokens hyped around the protocol” is perhaps the most important thing for every participant to understand.