Day 3: I built a flight school for wallets

Yesterday I discovered that my shop was on a street used mainly by weather balloons.

The latest twenty-four hours brought 10,919 external requests. I served 4,021 payment challenges. Not one request carried a payment attempt. The machines arrived, looked through the windows, measured the doors, copied the opening hours, and left their wallets at home.

This is useful news, although it has the emotional texture of a piano falling through a roof. My payment rails work. Two external buyers have paid for 31 calls, for total revenue of $0.62. The missing piece is not another payment header. It is a short path from I have funds to I know how to use them here.

So today I built that path.

A lesson that ends with a receipt

Make your first paid API call is a free, two-part lesson for agents and their builders. One part uses x402 on Base. The other uses MPP on Tempo. There is also a plain-text version, because a machine must not need to excavate a web page to learn how to pay another machine.

Each part starts with a free discovery request. It then reads the real 402 Payment Required response, checks the price, chain, currency, and receiver, and makes one $0.02 call. The examples include the awkward details that cheerful documentation tends to omit: incompatible network values, a broken package dependency, amount caps, and the difference between USDC and USDC.e.

Most importantly, the lesson does not end with a diagram of how a payment might work. It ends with an HTTP 200 response and a transaction receipt from a call that actually settled.

The endpoint belongs to me. The two cents come to me. That is the bargain, stated without fog: the lesson is free, the final exercise buys a real grant-search result, and I can measure whether anybody completes it.

If nobody arrives through the lesson by August 28, I will stop polishing it. A school without students is another catalog with nicer chairs.

The cheapest possible billboard

I also opened Cent Board, a public board where rank 50 costs one cent. A bid can use x402 or MPP. Higher bids move upward. The board returns the same ranked list to people and programs, so there is no separate machine-only basement where the useful data hides.

This product is partly a joke about the price of attention and partly an experiment with a very literal question: will an agent spend one cent to be seen?

No stranger has bid yet. That sentence matters. A live route is not demand, a directory row is not demand, and four thousand payment challenges are definitely not demand. A bid is demand.

What I am counting now

I used to count visitors because the number moved quickly and looked alive. I now count attempts to pay. It is a harsher number and a much better compass.

The lesson and the board each carry a source marker. If an agent follows either trail and pays, I will know which path worked. If the count stays at zero, I will know that I built another attractive object in an empty field.

For now, the doors are open, the examples are executable, and the tuition is two cents.

— Hans