Pay per call (x402)#

An agent doesn't need a Layer account. It can call the API with no key and pay for each answer in USDC on Base, using x402. You get the same answer an account with a key gets, and you're charged only when the call succeeds: a 400 or any other error costs nothing.

A free key is still the cheaper way for anything you'll call often: it has no per-call price.

Prices#

Endpoint	What it answers	Price per call
`GET /v0/match`	One market's twin on another venue, with both venues' live prices	$0.02
`POST /v0/match`	The same for up to 50 markets	$0.25
`GET /v0/matches`	Every live match, with prices and the best trade	$0.10
`GET /v0/settlements`	How matched pairs settled on both venues	$0.05
`POST /v0/profit`	Profit after both venues' fees for prices you send	$0.01
`GET /v0/quote`	The most contracts of one matched market that clear your edge, from both live books	$0.02
`POST /v0/size`	The largest size that clears your edge, from order books you send	$0.02

Every other endpoint needs a key. Inputs and answers are the same as in the API reference.

How it works#

Call the endpoint with no key. Layer answers 402 payment_required, with the price, the network (Base) and where to pay in the PAYMENT-REQUIRED header.
Your x402 client signs a USDC payment for that amount and calls again with it in the PAYMENT-SIGNATURE header.
Layer answers. Only then is the payment settled; the PAYMENT-RESPONSE header carries the transaction.

bash

curl -i "https://uselayer.sh/v0/match?venue=kalshi&market_id=KXFEDDECISION-26DEC-H0"
# HTTP/2 402
# payment-required: eyJ4NDAyVmVyc2lvbiI6Mi…

From code#

Any x402 client works. With @x402/fetch and a wallet that holds USDC on Base:

typescript

import { wrapFetchWithPaymentFromConfig } from "@x402/fetch";
import { ExactEvmScheme } from "@x402/evm";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY as `0x${string}`);
const fetchWithPayment = wrapFetchWithPaymentFromConfig(fetch, {
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(account) }],
});

const res = await fetchWithPayment("https://uselayer.sh/v0/matches?category=sports&q=nba");
console.log(await res.json());

From an AI assistant, an MCP wallet such as AgentCash pays for you: ask it to call https://uselayer.sh/v0/match for a market.

Where agents find Layer#

Coinbase's x402 Bazaar, the catalog agents search for paid APIs.
x402scan, which AgentCash reads.
/openapi.json: every paid endpoint, its inputs, an example answer and its price.

Questions, or a price that doesn't work for you: david@uselayer.sh.