PayAnyWhere

Problem Statement

At international events -especially within the crypto ecosystem- it's common for attendees to hold their funds in cryptocurrencies or stablecoins rather than in the host country's local currency. This creates friction when paying for tickets, merchandise, or on-site purchases. Some participants have crypto cards, but they often don't work locally, others prefer to avoid cumbersome conversions.Our solution:** PayAnyWhere** PayAnyWhere is a non-custodial, multi-chain payment layer that lets any merchant accept crypto from any network or token, while receiving everything in one unified settlement wallet. Merchants create a payment request in USD, the system generates a QR, and customers can pay using fiat or any compatible crypto asset on their preferred chain.When a customer pays with crypto, the protocol automatically handles the on-chain flow: swapping the selected token to USDC, bridging the funds to Polygon using LayerZero/Stargate, splitting the payment (99% merchant / 1% protocol), and depositing both shares directly into Aave.The entire flow is executed by smart contracts, with zero custody at any stage. PayAnyWhere delivers the simplicity of a traditional checkout while preserving full decentralization, unified balances, and merchant sovereignty.

Solution

We built PayAnyWhere using a fully modular, non-custodial architecture across backend, frontend, wallet infrastructure, and smart contracts. The backend is written in TypeScript with ExpressJS, hosted on Google Cloud Platform (GCP) for reliability, UX, scaling, and secure API orchestration. We use MongoDB to store merchant profiles, orders and QR sessions (payments).On the frontend, Next.js handles dynamic QR generation, the checkout interface, and wallet connections. For merchants and users who prefer embedded self-custody, we integrate Dynamic to create and manage non-custodial wallets directly within the experience, without compromising ownership.Our smart contracts were built with Foundry in Solidity. For cross-chain execution, we leverage LayerZero + Stargate to bridge USDC across networks. Before bridging, the system performs token-to-USDC conversion via the CDP Trade API for on-chain swaps, allowing customers to pay with a wide variety of tokens.On Polygon, our settlement contract Compose receives the bridged USDC, executes the 99/1 merchant/protocol split, and deposits both shares into Aave, giving merchants a unified, yield-generating settlement account that remains fully self-custodial.Overall, we stitched together swap, bridge, settlement, wallet, and yield layers into a single trustless pipeline—simple on the surface, but fully decentralized under the hood.