Autonomous agents — AI-powered programs that can think and transact without human input — may unlock a new world of e-commerce on Ethereum due to a largely forgotten HTTP web standard that has only recently been leveraged on the blockchain.
The dormant HTTP 402 “Payment Required” status — defined 30 years ago — together with Ethereum Improvement Proposal 3009, enables AI agents to make stablecoin transfers without human intervention, the Ethereum Foundation said on Wednesday, sharing a “guest thread” written by Coinbase development team members Kevin Leffew and Lincoln Murr.
The pair said in the X post that autonomous agents may become Ethereum’s “biggest power user.” Coinbase has already implemented HTTP 402 via the “x402 payments protocol,” according to its GitHub account.
The shift could be transformative because AI agents can now autonomously access funds to pay for services, eliminating the need for human intervention in managing API calls, storage or computation.
It could enable everything from self-driving taxis covering their own costs to AI models generating content on demand and apps automatically using stablecoins to store data permanently, the pair said.
In a limited manner, AI agents are already trading crypto by analyzing market data, executing buy or sell orders and optimizing portfolios in real time without human intervention.
As simple as a vending machine
Leffew and Murr compared the process to that of a vending machine, explaining that an AI agent receives an HTTP 402 request, signs a transaction, and makes the payment to get the response.
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It essentially turns the API into a wallet-aware service, they said.
“One round trip. Like a vending machine. No accounts required.”
Ethereum is the best fit for HTTP 402
Leffew and Murr said Ethereum’s trustless settlement layer makes it the ideal blockchain for HTTP 402 implementation, noting that it makes invoices and dispute chargebacks far more efficient than traditional processes.
“They need atomic payments, programmable policies, and composable wallets. Ethereum and stablecoins give them exactly that.”
AI agents are already being leveraged via HTTP 402, EIP 3009
Developers are already experimenting with HTTP 402, the Coinbase workers said, pointing to Hyperbolic Labs implementing it into its large language model and Prodia Labs generating images and video media content.
“The magic of x402 isn’t just that agents can pay, it’s that they can autonomously chain services into full economic loops,” Leffew and Murr concluded.
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