ArcPay — Four ways to get paid. One URL.

ArcPay is a unified payments primitive on Arc Network. One URL — arcpay.finance/@you — accepts four payment modes for humans and AI agents: 💸 Tips. One-time USDC with a message. A Chrome extension injects a ⚡ Tip button into every tweet on X. Tips for handles without a registered wallet are held on-chain keyed by the handle — claimable anytime via Twitter OAuth. 📅 Subscriptions. Monthly or yearly USDC with per-second accrual and auto-prorated refunds on cancel. 2% protocol fee vs Patreon's 10%. Demo: arcpay.finance/demo-blog. 🔒 Content paywall. Gate articles, videos, courses. Pay once, on-chain receipt forever — works even if the host disappears. Demo: arcpay.finance/demo-product. ⚡ Pay-per-call. x402-compatible / ERC-8183-ready billing for AI agents. batchPay(endpointId, N) prepays N inference credits in ONE transaction at 0.001 USDC/call. Each subsequent call is a wallet signature verified on-chain. Demo: arcpay.finance/demo-agent. Hackathon requirements met: • Per-action pricing: 0.001 USDC (10× under the $0.01 threshold) — verified on-chain via PayPerCall.getEndpoint(). • 54 on-chain demo txs across 5 contracts, all 4 payment modes exercised (verified on testnet.arcscan.app). Evidence pack: github.com/wanggang22/arcpay/tree/main/demo-video/hackathon-evidence. • Margin: nanopayments break on L1 (gas $0.50–$5 per call devours 99% of $0.001 revenue) and stretch on L2s (5–95% burn). On Arc, gas is native USDC and sub-cent. Our PayPerCall contract shows 6 txs compressing to 60 logical calls via batchPay — one transaction, ten prepaid credits, ten discrete signatures, settled in seconds. That economic model is impossible on any non-Arc chain today. Built solo in 3 days with Claude Code: 6 Solidity contracts (Foundry), TypeScript + Python SDKs (npm @wanggang22/arcpay-sdk + pip-from-git), Chrome extension v0.2.1 (MV3 zip at github.com/wanggang22/arcpay/releases), Next.js landing, Nextra docs, create-arcpay CLI scaffold. MIT at github.com/wanggang22/arcpay.