0xGateway

💡 Inspiration

Managing multiple wallet addresses across chains is messy — long hex strings, endless copy-paste, and constant risk of error. We wanted to make payments as simple as sending to @username.

That idea became 0xGateway Protocol — a universal username registry for all chains.

🚀 What It Does

0xGateway replaces complex wallet addresses with a single, human-readable username (e.g., @sandeep).
Users link wallets across Ethereum, Solana, Polygon, Starknet, Stellar, and more — and anyone can send crypto directly to their username.

• No copy-pasting long addresses
  
• Optional memo/tag support for CEX deposits
  
• Fully on-chain lookups via Gateway smart contracts
  

Example:

let wallet = gateway.get_wallet("@sandeep", "ETH");
transfer(wallet.address, amount);

👉 Send funds to @sandeep, not a 42-character address.

🧱 How We Built It

• Smart Contracts:
  Written in Cairo, deployed on Starknet Sepolia for registration, wallet linking, and on-chain queries.

• Frontend:
  Next.js + React with starknet.js integration for wallet connection and contract interaction.

• Architecture:

  User → Gateway Contract → Username Registry → Linked Wallets
  

  All username–wallet records are decentralized and immutable on Starknet.

• Deployment:
  Frontend: Vercel
  Contract: Starkscan Link

⚔️ Challenges

• Normalizing multi-chain address formats
  
• Integrating memos/tags within a unified wallet model
  
• Immature Starknet tooling and network delays
  
• Simplifying the wallet-linking UX for non-technical users
  

🏆 Accomplishments

• First cross-chain username registry on Starknet
  
• Working demo with live username registration and wallet linking
  
• Exchange-compatible memo/tag support
  
• Clean developer interface for easy contract use
  
• Proof of Starknet’s potential as the Web3 identity layer
  

📚 Learnings

• Cairo + Starknet excel at scalable identity mapping
  
• Cross-chain design requires flexible abstraction
  
• UX simplicity drives adoption more than features
  
• Decentralized naming can power next-gen DeFi, wallet, and DAO experiences
  

🌍 What’s Next

• Deploy across popular chains — Ethereum, Polygon, Arbitrum, Solana, Stellar
  
• Build TypeScript and Python SDKs
  
• Federated username resolution via REST/GraphQL APIs
  
• Partner with wallets to enable direct send-to-username
  
• Collaborate with dApps to make @handles the universal payment layer
  

💫 Summary

0xGateway turns blockchain addresses into human-friendly usernames — a decentralized identity layer for seamless, cross-chain payments.
Built with Cairo, powered by Starknet, designed for the next wave of crypto usability.

Built With

• cairo
• nextjs
• snforge
• starknet.js
• typescript