LiveArc · Base · Robinhood Chain

Pay per call with x402

No account, no API key, no subscription. An agent asks for a private model, gets a price, signs a stablecoin payment and gets its answer. Every payment settles on chain, and the part a call did not use is sent back.

How a call is paid

  1. Ask. POST /v1/chat/completions with no key. You get a 402 with the price in every stablecoin we take: a ceiling for your input plus max_tokens of output, never under 1 cent on Robinhood Chain.
  2. Sign. Your wallet signs a transfer authorization (EIP-3009) on the chain you hold dollars on. No gas token needed.
  3. Settle. Send the same request with the signature. A facilitator settles it on chain, and only then is the call served, inside a GPU enclave with no logs.
  4. Refund. The real charge is worked out from actual usage. The rest of the ceiling goes back to your wallet, on the chain you paid on.

Where you can pay

Robinhood Chain

USDG, straight from your wallet.

Settled by Priors

Base

USDC, straight from your wallet.

Settled by PayAI

Arc

USDC from a Circle Gateway balance, settled in batches.

Settled by Circle Gateway

A private Gloam balance

USDG cashed out of Gloam's vault on Robinhood Chain, never your wallet. Funds a prepaid key with no wallet attached.

Scheme gloam-cashout · /v1/gloam

Proof, on chain

Real payments to OffRouter, each one checkable on a block explorer. Who settled it is the account that sent the transaction.

First payment settled by Priors

Settled
When
7 November 2026, 05:24 UTC
What
A $1 prepaid key, paid in USDG on Robinhood Chain
Settled by
Priors, from its facilitator signer 0x81da…2319
Block
108,167,201
Transaction
0x2eab7f41…bcc25c4

Try it

curl -i -X POST https://offrouter.org/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{"model": "gpt-oss-120b", "max_tokens": 256,
       "messages": [{"role": "user", "content": "Hello"}]}'

That returns the 402 and its price. Any x402 client pays it: @x402/fetch, Coinbase's or Priors' payer, or our own MCP server. Many calls? Mint a prepaid key with one payment at POST /v1/keys. The full reference is in the docs, and every paid endpoint is listed at /.well-known/x402.