DeFi Protocol Templates

Production-ready templates for common DeFi protocols including staking, AMMs, governance, and flash loans.

When to Use This Skill

• Building staking platforms with reward distribution
• Implementing AMM (Automated Market Maker) protocols
• Creating governance token systems
• Integrating flash loan functionality

Staking Contract

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract StakingRewards is ReentrancyGuard, Ownable {
    IERC20 public stakingToken;
    IERC20 public rewardsToken;

    uint256 public rewardRate = 100; // Rewards per second
    uint256 public lastUpdateTime;
    uint256 public rewardPerTokenStored;

    mapping(address => uint256) public userRewardPerTokenPaid;
    mapping(address => uint256) public rewards;
    mapping(address => uint256) public balances;

    uint256 private _totalSupply;

    event Staked(address indexed user, uint256 amount);
    event Withdrawn(address indexed user, uint256 amount);
    event RewardPaid(address indexed user, uint256 reward);

    constructor(address _stakingToken, address _rewardsToken) {
        stakingToken = IERC20(_stakingToken);
        rewardsToken = IERC20(_rewardsToken);
    }

    modifier updateReward(address account) {
        rewardPerTokenStored = rewardPerToken();
        lastUpdateTime = block.timestamp;

        if (account != address(0)) {
            rewards[account] = earned(account);
            userRewardPerTokenPaid[account] = rewardPerTokenStored;
        }
        _;
    }

    function rewardPerToken() public view returns (uint256) {
        if (_totalSupply == 0) {
            return rewardPerTokenStored;
        }
        return rewardPerTokenStored +
            ((block.timestamp - lastUpdateTime) * rewardRate * 1e18) / _totalSupply;
    }