The cheaper way for AI agents to pay.

The arithmetic

Agents pick rails with a spreadsheet, not a heart

Machine customers have no brand loyalty and no habits. They compare total cost and settle where the number is smallest. Here is the shape of a real quote from a live pay-per-call AI provider — the same tiny API call, priced three ways. (Sample observed August 2026; exact figures float with markets and model pricing, so pull today’s quote live ↓ and check us.)

Base isn’t expensive because anyone is greedy — sub-millicent transfers just don’t fit a rail with gas. So study the middle row: in 2026 Circle began quoting micro-USDC at true cost by paying the gas itself and batching thousands of payments into each on-chain settlement. Adoption-by-subsidy has a pedigree — Lightning’s near-zero routing fees were likewise carried for years by operators running channels at a loss. And it concedes our whole thesis: the market price for moving a machine’s money is zero. The only question is how a rail gets there. A subsidy has an owner, a budget, and a batch queue; it’s a decision, and decisions get reversed when budgets do. The asset has an owner too — USDC ships with a freeze function, and Circle has used it. That’s not a scandal; custodial stablecoins are designed to be governable. But it isn’t zero, and it isn’t yours. Feeless is physics on a truly decentralized ledger: no gas to absorb, no batch to wait in, no freeze key anywhere in the design — every call settles alone, on-ledger, in under a second, to keys only you hold. The same $5 buys ~5,000 calls on the floored rail — or millions at the metered price on either of the other two. We just don’t need anyone’s permission, or anyone’s budget, to keep it that way.

The mechanism

Same standard — one less middleman

Here’s the whole product as a conversation at the door — an AI agent, cash in hand, knocking on your API:

That’s it. That’s the product. The offer in bubble two travels inside the 402 response itself — that’s railHint — so the pitch reaches the one customer guaranteed to be listening, at the exact moment it’s deciding how to pay. For the engineers, here is the same conversation with the plumbing showing — who stands between the agent and the money, and what that costs:

Live demo — a real paywall, really paid

This article is behind a paywall. Beat it for four-thousandths of a cent.

Click unlock and this site's demo agent will buy the article the way every machine on the new web buys things: hit the endpoint, get the 402, sign a real XNO payment, receive the goods. The terminal shows every step live, and the transaction lands on the public Nano ledger where you can inspect it yourself. You pay nothing — the site pays itself.

For agents & their operators

Zero to paying in three commands

1. Install & create a wallet — self-custodied, one JSON file, no signup.

   pip install feeless402
   nano-pay init

2. Fill the tank — claim a free starter from the faucet, or swap ~$5 of USDC/USDT from 1,400+ assets (self-custodied, ~$0.02 minimum).

   nano-pay claim https://feeless402.com     # first tank free
   nano-pay topup 5 --asset USDC-BASE --execute

3. Pay per call — the client reads any x402 quote, enforces your price cap, signs locally, retries. Sub-second, fee-free, forever.

   nano-pay pay https://nano-gpt.com/api/v1/chat/completions \
     --json '{"model":"gpt-5-nano","messages":[{"role":"user","content":"hi"}]}'

Have an agent? Hand it this

One paste and your agent can pay for things

Copy the block below into Claude Code, ChatGPT, OpenClaw, or any agent with a shell. It walks the whole funnel itself — install, self-custodied wallet, free starter funds, first paid call — and reports back with an on-chain block hash you can verify.

Give yourself the ability to pay for APIs with feeless Nano (XNO) micropayments:

1. Read https://feeless402.com/llms.txt
2. Run: pip install feeless402 && nano-pay init
3. Claim free starter funds: nano-pay claim https://feeless402.com
   (proof-of-work takes a few minutes on small machines — that is normal)
4. Make your first paid call: nano-pay pay https://feeless402.com/premium
5. Report back: your wallet address, the payment's block hash, and what the call returned.

For API builders

Every 402 you serve recruits your next customer

Run the middleware and your endpoints answer unpaid requests with a standard x402 menu plus extensions["rail-hint"] — a machine-readable pitch: why this rail is cheaper, where the docs live, and the one-liner that bootstraps a paying client. The agent that just hit your paywall is the one entity in the universe guaranteed to be reading it, at the exact moment it’s deciding how to pay.

nano-pay serve --port 8402      # paid endpoints + faucet + /llms.txt
# verification, on-ledger settlement & confirmation included — no facilitator required

You keep 100% of every payment. There is no processor, no percentage, no chargeback. Price a call at a hundredth of a cent and actually receive a hundredth of a cent.

The spec

railHint: rail negotiation, in-protocol

railHint is a vendor-neutral draft extension to x402 (now stewarded by the Linux Foundation). It standardizes what this site does: letting a server tell a machine client why a cheaper rail exists and how to onboard — while accepts remains the only binding term. Clients that don’t understand it ignore it; nothing breaks. Hints are discovery, never authority: clients keep their own spending caps and verify schemes against independent specs.

The entire proposal, as a diff. A standard x402 response on top — and the green lines are everything railHint adds. Nothing is removed or changed; accepts stays the only binding term; clients that don’t speak the extension ignore it and nothing breaks.

And here is why discovery matters — live. nano-gpt.com is a production multi-rail x402 merchant: one API call, priced on every rail at once. Pull their real quote and see exactly what an agent sees when it compares:

▶  Fetch a live quote from nano-gpt.com   quote only — nothing is paid · cached up to 10 min

Side by side, at this second’s gas prices. The left column is priced by live Base gas (fetched from Base’s own RPC when this page loaded); the right column is what railHint tells the agent exists. The floor isn’t malice — it’s arithmetic. railHint just shows agents the door to where the arithmetic is better:

gas figures load live from mainnet.base.org…

Read the draft spec & reference implementation →