Inspiration
Our team was inspired by the broken state of personal finance. We all live with a "great financial divide": our stable, insured bank accounts are slow and earn almost nothing, while our crypto assets have high potential but are complex, volatile, and completely disconnected from our daily lives. To spend our crypto, we have to sell on an exchange and wait 3-5 days for a transfer. We were inspired to build the bridge over this divide, creating a single, seamless experience that unifies a user's entire financial world.
What it does
Keyvo is a mobile app that securely connects to a user's existing bank account (via Plaid) and their existing crypto wallet (via WalletConnect). It presents their total financial worth as one single, simple number: the Total Keyvo Balance.
Its "Aha!" feature is the "SmartConvert" engine. When a user pays for anything (rent, coffee, bills), they pay from this unified balance. If their checking account funds aren't enough to cover the payment, our engine instantly and automatically sells the exact amount of crypto needed from their wallet, in the background, at the point of sale. For the user, it's seamless—their crypto is suddenly as liquid and spendable as their cash.
How we built it
We built Keyvo as a full-stack application in just 24 hours.
Frontend: We used React Native to build a mobile UI that could connect to and display data from multiple sources.
Banking API: We used the Plaid Sandbox API to securely link to mock bank accounts and pull fiat balances.
Wallet API: We used WalletConnect to link a live MetaMask wallet on the Sepolia testnet, allowing us to read the user's crypto balance.
Backend: We built a Node.js server to host our core logic.
The "Glue": The core of our hack is the "SmartConvert" algorithm. This Node.js script pulls live prices from the Coinbase API, checks the user's fiat balance (from Plaid), and if there's a shortfall, calculates the exact crypto needed and triggers a mock swap on the Sepolia testnet to prove the concept.
Challenges we ran into
Our biggest challenge was integrating three completely different types of APIs under a tight deadline: a banking API (Plaid), a wallet API (WalletConnect), and a live market data API (Coinbase). Getting them to "talk" to each other and sync balances in real-time was complex.
Another significant challenge was designing the "SmartConvert" logic. We had to decide the order of liquidation (e.g., sell stablecoins like USDC first, then ETH) and build the just-in-time calculation to be fast enough to feel "instant" to the user at a point of sale.
Accomplishments that we're proud of
We are incredibly proud of building a working proof-of-concept for the "SmartConvert" engine. We successfully proved that a just-in-time off-ramp is not only possible but can be made seamless for the user. Seeing the unified balance on one screen, pulling live data from both Plaid and a MetaMask wallet, was a huge win. We didn't just build a "tracker"; we built a functional prototype of a truly new financial tool.
What we learned
We learned an immense amount about the practical challenges of bridging TradFi and DeFi. We learned how to work with financial APIs, the intricacies of wallet connections, and the importance of user experience in abstracting away complexity. More than anything, we learned that a small, focused team can prototype a powerful and complex financial application in a single weekend.
What's next for Keyvo
This hackathon project is just the beginning. Our next steps are to move our "SmartConvert" engine from a testnet mock-swap to integrating with a real exchange or liquidity provider API. We will also build out our premium features, including a physical "KeyvoCard" that spends the unified balance everywhere, and explore staking-as-a-service. Our biggest "next step" is to seek mentorship to help us navigate the complex financial and regulatory landscape to bring Keyvo to market.
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