Coupon marché

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  this is the main design of the website

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  this is the marketplace

Inspiration

Consumers often accumulate vouchers and gift cards that go unused and eventually expire. Existing resale platforms are fragmented and rely heavily on manual verification, leading to fraud, scams, and lack of trust between buyers and sellers. We wanted to build a secure, trustless, and automated system where unused vouchers can be safely converted into real value—without intermediaries, disputes, or risk.

What it does

Coupon Marché is a secure marketplace that allows users to buy and sell unused vouchers safely. It ensures trust between buyers and sellers by using automated verification, escrow-based payments, and transparent transactions, eliminating common voucher fraud such as invalid or already-used coupons. The platform guarantees that sellers get paid fairly and buyers receive valid vouchers they can confidently redeem.

How we built it

We built Coupon Marché using a modern full-stack and blockchain-oriented approach: Frontend: Next.js for a fast, responsive, and user-friendly interface Backend: Server-side logic integrated directly into Next.js for verification and processing Blockchain Layer: Smart contracts to handle escrow, ownership transfer, and secure payments Off-chain Storage: IPFS for storing voucher metadata securely Automation: Smart contract logic ensures vouchers are released only after successful verification and redemption conditions are met This architecture removes manual intervention and creates a trust-minimized flow.

Challenges we ran into

Designing a trustless escrow mechanism that works seamlessly for digital vouchers Preventing double-spending or reused voucher fraud Balancing on-chain security with off-chain efficiency Integrating blockchain interactions smoothly into a user-friendly frontend Ensuring clear user flows for both buyers and sellers with minimal friction

Accomplishments that we're proud of

Built a fully functional escrow-based voucher marketplace Eliminated the need for manual verification or third-party trust Designed a clean, intuitive UI despite blockchain complexity underneath Created a scalable foundation that can support multiple brands and voucher types Successfully demonstrated a real-world use case for secure digital asset exchange

What we learned

How to design secure escrow workflows using smart contracts Practical trade-offs between on-chain and off-chain systems Improving UX for blockchain-based applications Handling edge cases in trustless transactions Collaborating efficiently under hackathon time constraints

What's next for Coupon marché

Support for more brands and voucher categories AI-powered voucher authenticity checks Mobile app integration Multi-chain support for lower fees and faster transactions Partnering with merchants for direct voucher issuance Advanced analytics and reputation systems for sellers

Built With

• ethereum
• ethers.js
• hardhat
• ipfs
• next.js
• react
• solidity