x402kapy SDK

KAPY & USDC payment configs for the x402 protocol on Base.

Install

npm install x402kapy @x402/next @x402/core @x402/evm

Quick Start

Protect a Next.js API route

// app/api/premium/route.ts
import { withX402 } from "@x402/next";
import { x402ResourceServer, FacilitatorClient } from "@x402/core";
import { ExactEvmScheme } from "@x402/evm";
import { kapyAccepts, BASE_MAINNET } from "x402kapy";

const facilitator = new FacilitatorClient({ url: "https://facilitator.x402.org" });
const server = new x402ResourceServer(facilitator)
  .register(BASE_MAINNET, new ExactEvmScheme());

const handler = async (request: NextRequest) => {
  return NextResponse.json({ data: "premium content" });
};

export const GET = withX402(handler, kapyRoute({
  price: "1",         // 1 KAPY or 1 USDC
  tokens: "both",
}), server);

Discover available services

import { discover } from "x402kapy";

const { items } = await discover();
for (const service of items) {
  console.log(service.metadata.name, service.resource);
}

API

Constants

| Export | Value | |--------|-------| | KAPY | { address, decimals: 18, symbol: "KAPY", ... } | | USDC | { address, decimals: 6, symbol: "USDC", ... } | | BASE_MAINNET | "eip155:8453" | | BASE_SEPOLIA | "eip155:84532" | | DEFAULT_PAY_TO | "0xc406fFf2Ce8b5dce517d03cd3531960eb2F6110d" | | CATEGORIES | ["api", "ai", "data", "storage", "compute", "mcp", "infrastructure", "other"] |

kapyRoute(opts)

Builds x402 RouteConfig for KAPY and/or USDC payments. Pass to withX402().

| Option | Default | Description | |--------|---------|-------------| | price | required | Human-readable price (e.g. "1", "0.5") | | payTo | DEFAULT_PAY_TO | Address receiving payment | | tokens | "both" | "kapy", "usdc", or "both" | | network | BASE_MAINNET | Network identifier | | description | "" | What the buyer gets | | mimeType | "application/json" | Response MIME type | | timeoutSeconds | 60 | Payment timeout |

toAtomic(price, token) / fromAtomic(atomic, token)

Convert between human-readable and on-chain atomic units.

toAtomic("1", KAPY)    // "1000000000000000000"
toAtomic("0.5", USDC)  // "500000"
fromAtomic("1000000000000000000", KAPY)  // "1"

discover(baseUrl?)

Fetch the x402kapy Bazaar-compatible discovery endpoint. baseUrl defaults to https://x402kapy.moikapy.workers.dev.

kapySchemes()

Returns scheme registrations for Base mainnet. Requires @x402/evm peer dependency.

License

MIT