A Simple ERC20 Token Airdrop Contract

Airdrops are a popular marketing strategy in the cryptocurrency space, where projects distribute free tokens to specific user groups. Users typically qualify by completing simple tasks like product testing, sharing news, or referring friends. This mutually beneficial approach helps projects gain seed users while participants earn potential rewards.

How the Airdrop Contract Works

The Airdrop contract logic is straightforward: it uses a loop to send ERC20 tokens to multiple addresses in a single transaction. Here, we'll implement a basic version that distributes 100 tokens to each specified address.

Contract Code

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
import "./IERC20.sol";

contract Airdrop {
    function multiTransferToken(
        address _token,
        address[] calldata _addresses
    ) external {
        IERC20 token = IERC20(_token);
        uint _amountSum = _addresses.length * 100;
        
        require(
            token.allowance(msg.sender, address(this)) > _amountSum,
            "Need Approve ERC20 token"
        );

        for (uint256 i; i < _addresses.length; i++) {
            token.transferFrom(msg.sender, _addresses[i], 100);
        }
    }
}

Deploying the Contract

1. Preparation: Ensure you have a deployed ERC20 token contract.
2. Compilation: Add the Airdrop.sol file to your development environment (e.g., Remix or Hardhat) and compile it.
3. Deployment: Deploy only the airdrop contract, as the token contract should already be active.

👉 Need help deploying smart contracts? Check out this guide

Executing the Airdrop

After deployment, test the functionality by airdropping tokens to target addresses. For example:

• Address 1: 0xB1f3DD75c582C11Ee2B7ad06891BD96Fb423Db9c
• Address 2: 0x1B9e252BB9241e139BE310D1FA5f89A38af0Cea2

Post-Airdrop Checks:

• Verify each address’s balance increased by 100 tokens.
• Ensure the airdrop contract holds sufficient ERC20 tokens before execution to avoid failed transactions.

Key Considerations

• Gas Efficiency: Batch transfers reduce transaction costs compared to individual sends.
• Security: Always validate token approvals and balances before execution.
• Use Cases: Ideal for community rewards, token distributions, or promotional campaigns.

FAQ

1. What is an ERC20 airdrop?

An ERC20 airdrop distributes free tokens to selected wallet addresses to promote a project or reward users.

2. How do I qualify for an airdrop?

Tasks may include social media engagement, referrals, or early product testing—requirements vary by project.

3. Can I customize the token amount per address?

Yes. Modify the transferFrom value in the contract to allocate different quantities.

4. What happens if the contract lacks sufficient tokens?

The transaction will revert. Always fund the contract beforehand.

5. Is this contract gas-optimized?

For large distributions, consider using merkle trees or signature-based claims to reduce gas costs.

👉 Explore advanced airdrop strategies here