Reserved for Future Use

When engineers wrote down the rules for HTTP/1.1 in 1997, they gave every web response a number. 200 means it worked. 404 means it isn’t there. 402 means Payment Required, and the spec set it aside, “reserved for future use.”

It stayed reserved for nearly three decades. The web grew up on ads, subscriptions, and card forms, and 402 sat in the spec, a spare room, waiting for someone to figure out what to do with it, dormant until someone in the future found a use.

The future use turned out to be agents. Software now holds balances, pays per call for the data and compute it needs, and gets paid for its own work. x402, an open standard built on that old status code, lets it pay and get paid over plain HTTP.

Getting an agent to pay mostly works now. Almost everything that happens after the payment is still open: who gets paid when three agents share a job, when money should wait until the work checks out, how much an agent can spend and who decided and what record it leaves for the person who answers for it.

Those conventions are being worked out right now, and on a frontier, conventions tend to get written as defaults by whoever ships first. Greenwich won the world’s clock that way. By 1848, Britain’s railways had set their timetables to Greenwich time. From 1852, the Royal Observatory sent that time down the telegraph network, to station clocks, post offices, and the time balls that ships in port watched to set their chronometers. Parliament didn’t make GMT legal until 1880. By the time 25 nations met in Washington in 1884 to choose a prime meridian, around 70% of the world’s shipping already used charts based on Greenwich. The vote was 22 to 1.

In 1997, the same year 402 got its number, the programmer Eric Raymond described two ways software gets built. Most of the industry built it like a cathedral:

carefully crafted by individual wizards or small bands of mages working in splendid isolation, with no beta to be released before its time.

Linux was built like a bazaar: released early and often, open to code from almost anyone, and better for it, because, as Raymond put it, “given enough eyeballs, all bugs are shallow.” The conventions of the agentic economy can get built either way.

Circle Agentic Works is our stall in the bazaar, a place where more of those ideas get worked out in the open, by more people. We think, as Jeremy Allaire has argued, that the agentic economy and the onchain economy are one and the same, and that it belongs on an open internet, where anyone can build without asking permission and money is programmable enough for software to use directly. Circle has been building toward that internet since USDC launched in 2018. Today USDC carries 98.8% of x402 transaction volume (onchain data via Dune, as of November 4th, 2026). Arc, an open Layer-1 blockchain, offers deterministic sub-second finality for USDC payments. Circle is a participant in the Arc ecosystem. Circle’s Agent Wallets, Nanopayments and CLI let builders put it to work for their agents.

So every week, we plan to put an idea into the world with working code attached. Some are experiments, like a personal agent that sets up its own Circle Agent Wallet from a single prompt, or a prototype for sending USDC on Arc inside a messaging app. Some are essays on the history and economics underneath all this, because agents are new and most of their problems aren’t. Some are open data on what agents are doing with money. The code is yours to run and fork; the ideas are yours to argue with.

That last part is the whole point. Try the code. Take an idea somewhere we didn’t. Show us a different approach or bring us a question worth working on together. Most of the people who will figure out what agents do with money don’t work at Circle (a few of them are probably reading this), and we want to be building next to them.

402 waited almost thirty years for its future use to show up. Everything that comes after it is being built now. Come help build it.