# Building a DeFi Staking Platform with Solidity, Foundry, and Next.js on Ethereum Sepolia

As part of my EtherAuthority Web3 Training, I built a full-stack **DeFi Staking Platform** to gain practical experience in smart contract development, ERC-20 tokens, blockchain testing, and Web3 frontend integration.

The project was developed and deployed on the **Ethereum Sepolia testnet**.

## Project Objective

The main objective was to build a decentralized staking application where users can connect their wallet, approve and stake ERC-20 tokens, withdraw their staked tokens, and claim rewards generated according to the staking contract's APR.

The project also gave me hands-on experience with Foundry-based testing and integrating deployed Solidity contracts with a Next.js frontend.

## Technologies Used

* Solidity
* Foundry
* OpenZeppelin
* Next.js
* TypeScript
* ethers.js
* MetaMask
* Ethereum Sepolia
* Vercel

## Smart Contracts

The project contains three main Solidity contracts.

### 1. StakeToken

`StakeToken.sol` is an ERC-20 token named **Stake Token (STK)**.

The contract mints an initial supply of **100,000 STK** to the deploying account.

### 2. RewardToken

`RewardToken.sol` is an ERC-20 token named **Reward Token (RWD)**.

The contract mints an initial supply of **1,000,000 RWD** to the deploying account.

### 3. Staking

`Staking.sol` manages the staking process and reward calculation.

The main functions include:

* `stake()` — deposits STK into the staking contract.
* `Withdraw()` — withdraws previously staked STK.
* `claimRewards()` — claims accumulated RWD rewards.
* `setAPR()` — allows the owner to update the APR.
* `pause()` / `unpause()` — allows the owner to pause and resume staking-related operations.

The contract also uses OpenZeppelin components such as `SafeERC20`, `Ownable`, `Pausable`, and `ReentrancyGuard`.

## How Staking Works

The user first connects their MetaMask wallet to the application.

Before staking, the user approves the staking contract to spend a selected amount of STK tokens.

The user can then stake the approved amount.

The staking contract records the user's staked balance and updates the reward calculation based on the amount staked, the configured APR, and the time elapsed.

Users can later withdraw their staked tokens or claim their accumulated rewards.

## Frontend

The frontend was built using **Next.js, TypeScript, and ethers.js**.

The application connects to MetaMask through the browser wallet provider and reads blockchain data directly from the deployed contracts.

The dashboard displays:

* STK wallet balance
* Staked STK
* Pending rewards
* RWD wallet balance
* Current APR

The application also displays transaction hashes after blockchain transactions so that transactions can be verified on the Sepolia network.

## Foundry Testing

I used Foundry to test the staking contracts before working with the deployed application.

The tests cover:

* Constructor token addresses
* Successful staking
* Successful withdrawal
* Zero-amount staking
* Withdrawal greater than the staked balance
* Claiming without rewards
* Reward claiming
* Owner APR updates
* Non-owner APR restrictions
* Contract pause
* Contract unpause
* Invalid zero APR

These tests helped verify the core contract behavior and important edge cases.

## Ethereum Sepolia Deployment

The contracts were deployed on Ethereum Sepolia.

### Contract Addresses

**Staking Contract**

`0x1873eca046e15b910da2ea9ad50fce9fd695b0a7`

**Stake Token (STK)**

`0xaba6599a21cf3fa1bcf4038eb225f829bdb17cf5`

**Reward Token (RWD)**

`0x36070c3ad6efa8045d87e97e627dcb0eced73279`

## Challenges

One of the practical challenges was ensuring that the frontend correctly interacted with the deployed contracts and displayed the connected wallet's blockchain data.

I also worked through the complete approval → staking → withdrawal/reward flow and verified transactions on the Sepolia testnet.

Another important part of the project was testing contract behavior with Foundry before using the deployed contracts through the frontend.

## Live Project

The frontend is deployed and available online, and the complete source code is available on GitHub.

**GitHub Repository:**
https://github.com/PranshuMishra2004/DeFi-Staking-Platform

**Live Project:**
https://de-fi-staking-platform-opal.vercel.app/

## Conclusion

Building this DeFi Staking Platform gave me practical experience beyond writing individual Solidity contracts. I worked through the complete process of developing smart contracts, testing them with Foundry, deploying them to Ethereum Sepolia, and connecting them to a Web3 frontend using MetaMask and ethers.js.

This project has strengthened my understanding of Solidity, ERC-20 token interactions, staking mechanisms, smart contract testing, and decentralized application development.

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