RentChain 🏠⛓️

A decentralized rental marketplace on Ethereum — owners list properties, tenants pay rent in ETH directly to a smart contract. No broker, no middleman, no central database.

Tech: Solidity 0.8.24 · Hardhat · ethers.js · MetaMask · Mocha/Chai

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Demo

List a property, browse available rentals, and withdraw earnings — every action is a transaction against the on-chain smart contract, signed through MetaMask.

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What it does

Traditional rental platforms (NoBroker, 99acres, MagicBricks) run on a central server that owns the data, can take listings down, and inserts brokers between you and the owner. RentChain replaces that server with an Ethereum smart contract:

• 🔓 Listings live on-chain — public and tamper-proof; no one can secretly alter or delete them.
• 💸 Rent flows peer-to-peer — tenants pay the contract, which credits the owner directly.
• 🔐 Wallet = identity — users authenticate with MetaMask; no accounts, no passwords.
• 🛡️ Secure withdrawals — owners pull their earnings via the pull-payment pattern, avoiding re-entrancy and stuck-funds bugs.

It's a compact, end-to-end DApp demonstrating the three pillars of blockchain development: immutable storage, smart-contract logic, and trust-less value transfer.

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Architecture

+--------------------+         +-------------------------+
|   Browser (DApp)   |         |   MetaMask Extension    |
|   index.html       | <-----> |  (wallet + signer)      |
|   app.js (ethers)  |         +-----------+-------------+
+---------+----------+                     |
          |                                | signs tx
          | JSON-RPC (http://127.0.0.1:8545)
          v                                v
+-------------------------------------------------------+
|             Hardhat local Ethereum network            |
|        +-----------------------------------+          |
|        |   RentalMarket.sol  (deployed)    |          |
|        |   - properties[id]                |          |
|        |   - balances[owner]               |          |
|        |   - listProperty / rentProperty   |          |
|        |   - withdraw / endLease           |          |
|        +-----------------------------------+          |
+-------------------------------------------------------+

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Smart-contract API (RentalMarket.sol)

Function	Purpose
listProperty(location, description, rentPerMonthWei)	Owner adds a property to the marketplace.
rentProperty(id, months) payable	Tenant pays exact rent × months; lease end is recorded on-chain.
endLease(id)	Owner ends an expired lease — the property becomes vacant.
unlist(id)	Owner removes a vacant property.
withdraw()	Owner withdraws collected rent (pull-payment).
getAllProperties()	Returns all listings — read by the frontend.

Events: PropertyListed, PropertyRented, LeaseEnded, PropertyUnlisted, Withdrawn — the frontend listens to these to react to on-chain state changes.

Why pull-payment? Forwarding ETH inside rentProperty() would expose the contract to re-entrancy attacks and stuck-funds DoS. Instead, rent is credited to balances[owner] and the owner calls withdraw() themselves — the textbook secure pattern (OpenZeppelin PullPayment).

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Tests

8 unit tests (Mocha + Chai) covering the happy path, access control, and every input-validation branch:

npx hardhat test

RentalMarket
  ✔ lists a property
  ✔ rejects listing with zero rent
  ✔ lets a tenant rent and credits the owner balance
  ✔ rejects renting your own property
  ✔ rejects wrong rent amount
  ✔ rejects renting an already-rented property
  ✔ lets owner withdraw earnings via pull-payment
  ✔ rejects withdraw when there is nothing to withdraw

  8 passing

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Run it locally

Prerequisites: Node.js ≥ 18 · Chrome + MetaMask

npm install

Open three terminals:

# 1. Start a local Ethereum node (prints 20 funded test accounts)
npx hardhat node

# 2. Deploy the contract (auto-writes address + ABI to the frontend)
npx hardhat run scripts/deploy.js --network localhost

# 3. Serve the frontend
npx http-server frontend -p 5500 -c-1 -o

One-time MetaMask setup: add a network — RPC http://127.0.0.1:8545, Chain ID 31337, currency ETH — then import any private key printed by hardhat node (each comes with 10,000 test ETH).

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Demo flow

1. Connect MetaMask — your wallet address appears.
2. List a property (e.g. BTM Layout, 2BHK, 0.01 ETH/month) → confirm the tx → it appears in the grid.
3. Switch to a different account → Rent it for 2 months (value: 0.02 ETH) → confirm.
4. Card updates to "Rented until …".
5. Switch back to the owner → withdrawable balance shows 0.02 ETH → Withdraw → ETH lands in the wallet.

The entire rental cycle — list, rent, pay, withdraw — with no server in the middle.

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Project structure

├── contracts/RentalMarket.sol    # the smart contract
├── scripts/deploy.js             # deploys + writes ABI to frontend
├── test/RentalMarket.test.js     # 8 unit tests
├── frontend/                     # index.html + app.js (ethers.js) + style.css
├── hardhat.config.js
└── package.json

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Roadmap

• Security deposit held in escrow
• IPFS-stored property images
• On-chain reputation/rating for tenants & owners
• Sepolia testnet deployment (the same contract runs unchanged on any EVM network)

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A self-contained learning project exploring Ethereum smart-contract development, the pull-payment pattern, and connecting a browser DApp to the chain via MetaMask.