@wanggang22/arcpay-sdk

📦 Published under @wanggang22 scope for now. An @arcpay npm org is planned post-hackathon; package will be mirror-published there with version parity.

USDC payment primitive for creators, apps, and AI agents on Arc Network.

Tips · Subscriptions · Content paywalls · Pay-per-call API billing — one SDK, four payment modes, 2% fee, no Stripe, no KYC, works with email or wallet. Pay humans and AI agents.

Live at arcpay.finance · Full docs at arcpay.finance/build · Source on GitHub.

Install

npm install @wanggang22/arcpay-sdk viem

Quickstart

import { ArcPayClient } from '@wanggang22/arcpay-sdk';

const client = new ArcPayClient({
  network: 'testnet',
  privateKey: process.env.PRIVATE_KEY as `0x${string}`,
});

// 💸 Send a tip
await client.tips.send({
  username: 'gavin',
  amount: '0.005',
  message: 'Loved your post!',
});

// 📅 Subscribe for N months
await client.subs.subscribe({ planId: 0n, months: 3 });

// 🔒 Buy paywalled content
await client.paywall.purchase(contentId, priceWei);

// ⚡ Prepay 100 API credits in one tx (x402 / ERC-8183)
await client.api.batchPay('gavin', 'summarize-paper', 100);

Get free testnet USDC at arcpay.finance/faucet.

Four payment modes

| Mode | Typical use | Contract | |---|---|---| | 💸 Tip | One-time support, BuyMeACoffee-style | TipJar | | 📅 Subscribe | Monthly/yearly, Patreon-style | Subscriptions | | 🔒 Content Paywall | Single-item purchase, Gumroad-style | ContentPaywall | | ⚡ Pay-per-call API | Prepaid API credits, agent-friendly | PayPerCall |

Read-only gating (no database)

The chain is your subscriber list. Check active subscription on any wallet with two RPC calls:

const isActive = await client.subs.isActive(wallet, planId);
if (isActive) renderPremiumContent();

Same pattern works for Content and PayPerCall.

x402-compatible agent payments

// Agent prepays 1000 calls; SDK auto-signs each HTTP request
await client.api.batchPay('creator', 'endpoint-name', 1000);
const result = await client.api.call('creator', 'endpoint-name', { input });

Server verifies receipts[callId].payer equals signature recovery address. No API key, no OAuth.

Network support

| Network | chainId | RPC | |---|---|---| | Arc Testnet | 5042002 | https://rpc.testnet.arc.network | | Arc Local | 1337 | http://localhost:8545 |

USDC is the native gas token on Arc — one currency for fees and payments.

Contract addresses (Arc Testnet)

Canonical source: contracts/deployments/current.json

• UsernameRegistry: 0xBF6c8b430BE134C40fEF316601ef002a4F8e2dBb
• TipJar: 0x45daE58fB5b89C4E994216D2af0B73232641DF3B
• TipJarByHandle: 0x291b86d46027f734cF43Eca9BA2394F46dcd529C
• Subscriptions: 0xbb84078Aa19b9c5Eb397782dE9b58939C38d1380
• ContentPaywall: 0x680884124F21939548Ba7f982B4F275A55783484
• PayPerCall: 0x3a399A310965A5cbD5a2B9F21a3B9885B6372def

Developer docs

Full API reference + integration recipes (Next.js blog, Discord bot, Express middleware, AI agent):

👉 arcpay.finance/build

License

MIT · © 2026 ArcPay contributors