faucet for demo dapp https://mumbai.polygonscan.com/address/0xbc3981f910f75b74271E382364a6Aac22A25BD7B

faucet.sol

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

import "./IERC20.sol";

contract Faucet {
    address public owner;
    // USDC token contract interface
    IERC20 public usdc;
    // USDT token contract interface
    IERC20 public usdt;
    // timestamp of last token send
    uint256 public lastSend;
    // mapping of users and last drip time
    mapping(address => uint256) public lastDrip;

    // constructor sets token contract addresses and lastSend to current time
    constructor(address _usdcAddress, address _usdtAddress) {
        owner = msg.sender;
        usdc = IERC20(_usdcAddress);
        usdt = IERC20(_usdtAddress);
        lastSend = block.timestamp;
    }

    // send tokens to user if 24 hours have elapsed since last drip
    function drip(address user) public {
        require(block.timestamp >= lastDrip[user] + 1 days, "24 hours have not elapsed since last drip");
        require(usdc.balanceOf(address(this)) >= 25e6, "USDC balance insufficient");
        require(usdt.balanceOf(address(this)) >= 25e18, "USDT balance insufficient");
        require(usdc.transfer(user, 25e6), "USDC transfer failed");
        require(usdt.transfer(user, 25e18), "USDT transfer failed");
        lastDrip[user] = block.timestamp;
    }

    // allow users to deposit USDC tokens
    function depositUSDC(uint256 amount) public {
        require(usdc.transferFrom(msg.sender, address(this), amount), "USDC transfer failed");
    }

    // allow users to deposit USDT tokens
    function depositUSDT(uint256 amount) public {
        require(usdt.transferFrom(msg.sender, address(this), amount), "USDT transfer failed");
    }

    // allow owner to withdraw all tokens from the contract
    function withdrawAll() public {
        require(msg.sender == owner, "Only the owner can withdraw tokens");
        uint256 usdcBalance = usdc.balanceOf(address(this));
        uint256 usdtBalance = usdt.balanceOf(address(this));
        usdc.transfer(msg.sender, usdcBalance);
        usdt.transfer(msg.sender, usdtBalance);
    }

    // get the balance of both USDC and USDT tokens
    function getBalance() public view returns (uint256 usdcBalance, uint256 usdtBalance) {
        return (usdc.balanceOf(address(this)), usdt.balanceOf(address(this)));
    }
}

IERC20.sol

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
}