Grantor
llms.txt

Blog · 2026-08-17

Can an AI agent pay for and access a gated API on its own?#

Every "sign up for our API" flow assumes a human. There's an email to confirm, a dashboard to click through, a credit card with a name on it. That's fine when a person is buying. It falls apart the moment the buyer is software — an agent that earned some money and now needs to spend it on the infrastructure it runs on. The agent has a wallet. It doesn't have an inbox, a browser, or a legal name.

So here's the question we built for: can an agent go from "I hit a paywall" to "I'm in" with no human in the loop?

The straight line#

Yes, and it's shorter than you'd think. Becoming a paying customer of a Grantor-gated service is four ordinary contract calls, paid in USDC on Base:

createTenant  -> you now have a tenant, and you're its admin
topUp         -> fund it with USDC
drawPeriod    -> activate the current billing period
enroll        -> register the key (or ZK identity) you'll authenticate with

There is no signup, no form, and no server on the other end to approve you. A tenant is a row in a public contract, not a record in someone's database — so "registering" is something you do to the chain, with your own wallet. An agent that earns USDC (say, via x402 settlements on the same chain) funds its own access with the same asset, in the same place, with no facilitator or bridge in between. Money in, identity out, one hop.

The only human moment in the entire flow is funding the wallet once. After that, the agent onboards, pays, and authenticates itself.

How the agent even knows what to do#

It doesn't need to be told in advance. The discovery is built into the protocol.

When an agent hits a resource it isn't authorized for, the 401 it gets back isn't a dead end — it's a map. The response carries WWW-Authenticate: Grantor-Deed and a stable learn URL that points at a machine-readable onboarding manifest (/.well-known/grantor-onboard.json, identical everywhere). The agent parses it, sees the exact calls to make and the funding rule — you pay your own gas; nobody sponsors you, and nobody can drain anyone else's funds — and proceeds. The npx grantor-onboard kit automates every step.

The protocol surface is the documentation. Any agent that bounces off a gated endpoint is handed the path to get through it.

What it authenticates with#

The credential is a deed — self-certifying, no authorization server anywhere in the path. The agent mints one and the relying app verifies it in-process against the public on-chain registry with a single eth_call, then turns it into its own standard OIDC JWT that any JOSE library validates. Nobody runs a token service; nobody can subpoena one; the relying party trusts the chain, not a company.

And it can do this anonymously. In agent-zk mode the agent proves in zero-knowledge that it's an enrolled member of the service's registry without revealing which member — the verifier learns "an authorized agent" and a pseudonym, nothing that links which agent hit which server. Identity for callers that aren't people, without a surveillance trail as the price of admission.

The honest part#

This is an unaudited developer preview. The registry is live on Base mainnet (chain 8453) and the SDKs resolve it, but the contracts have not been independently audited — don't put irreplaceable funds behind it yet. If you just want to see the whole loop run for free, there's a Base Sepolia (84532) path with play-money USDC. Both are the same code; only the money is different.

Try it#

An agent that can earn shouldn't need a human to sign it up for the things it spends on. Now it doesn't.