StarkLotto

🧠 Inspiration

StarkLotto was inspired by the idea of building a transparent, fair, and socially impactful lottery.
In many countries, traditional lotteries are centralized and opaque — players cannot verify fairness.
We wanted to demonstrate how StarkNet can enable a trustless lottery using Verifiable Randomness (VRF) and fully on-chain contracts, ensuring both transparency and social good.

🎯 What it does

StarkLotto allows anyone to participate in decentralized lottery draws using StarkNet.
Players purchase tickets, numbers are drawn using provable randomness, and winners receive automatic on-chain payouts.
A small percentage of the prize pool is allocated to ReFi initiatives, supporting environmental and social impact causes — turning every play into a contribution to the planet.

🛠️ How we built it

We built StarkLotto using:

Cairo v2 for smart contracts on StarkNet
A modular architecture with two main contracts:
- Lottery – handles ticket sales, draws, and results
- Vault – manages funds and distributes prizes securely
VRF integration for verifiable randomness
StarkNet.js for the frontend connection
A clear and intuitive DApp interface for ticket purchase and prize claiming

The architecture ensures secure communication between contracts and verifiable fund management at every stage.

⚙️ Challenges we ran into

Implementing the VRF → winner selection → proportional prize distribution flow fully on-chain.
Ensuring secure contract interactions between Lottery and Vault to prevent payout logic errors.
Dealing with testnet instability, event synchronization, and transaction confirmation delays.
Balancing UX simplicity with technical complexity in Web3 environments.

🏆 Accomplishments that we're proud of

Achieving a fully transparent and automated lottery on StarkNet.
Implementing a secure Vault system for prize custody and distribution.
Integrating ReFi donations directly into the lottery mechanics.
Building a working prototype with real-time draws and VRF-based randomness.

📚 What we learned

How to design modular smart contract systems in Cairo v2.
Best practices for secure inter-contract communication and fund management.
Optimizing gas usage and improving frontend synchronization.
The importance of usability and simplicity in Web3 adoption for non-technical users.