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Blockchain · Mini Project
Provably Fair Lottery DApp with Chainlink VRF
A lottery whose winner is picked by verifiable on-chain randomness
1-2 weeks build
Overview
Players enter a round with a fixed amount of test ETH, and when the round closes the contract requests a random number from Chainlink VRF, whose proof is checked on-chain before the winner is chosen. Chainlink Automation closes rounds on a timer. The report explains why block hashes are not safe randomness. Runs on Sepolia with test ETH and test LINK only; no real money is ever wagered.
What makes it stand up
- 01Winner chosen with Chainlink VRF verifiable randomness
- 02Timed rounds closed by Chainlink Automation
- 03Fixed entry fee in test ETH
- 04Local tests with the VRF coordinator mock
- 05Sepolia testnet only, never real money
Module breakdown
- 01
Lottery contract
Tracks entries, round state and the prize pool.
- 02
Randomness
Requests and receives VRF words to pick the winner.
- 03
Automation
Upkeep checks that close each round on time.
- 04
Tests
Hardhat tests using the VRF coordinator mock.
- 05
Frontend
React page for entering and viewing past winners.
After this, you will be able to
- Explain why block hashes can be manipulated as randomness
- Defend how the VRF proof makes the draw verifiable
- Demo a full round from entry to paid winner on Sepolia
Technology stack
- Solidity
- Chainlink VRF
- Hardhat
- ethers.js
- React
- Level
- Mini Project
- Domain
- Blockchain
- Build time
- 1-2 weeks
- Difficulty
You receive
- Complete, commented source code
- 60-90 page project report (IEEE format)
- Editable presentation deck
- Architecture, ER and UML diagrams
- Local setup and deployment guide
- Sample dataset or seed data
- Viva question bank with answers
- One 45-minute walkthrough call
- 30 days of doubt-clearing support