EIP-2771 Explained: How to Build Gasless dApps (with minimal code example)

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EIP-2771: Let Your Users Skip the Gas Station :fuel_pump:

Ever wished your users could use your dApp without needing ETH for gas? That’s exactly what EIP-2771 solves.

The Problem

New users face a frustrating chicken-and-egg problem:

  • They want to try your dApp
  • But they need ETH for gas
  • But they need to buy ETH first
  • …and they leave :cry:

The Solution: Meta Transactions

With EIP-2771, users sign transactions (free!) and a relayer submits them on-chain (pays gas).

User signs ──:play_button: Relayer pays gas ──:play_button: Forwarder ──:play_button: Your Contract :white_check_mark: Free! :money_with_wings: :package: :bullseye:

How It Works (The Magic)

  1. User signs a message with their intent (e.g., “transfer 100 tokens to Bob”)
  2. Relayer wraps it and sends to a Trusted Forwarder
  3. Forwarder verifies signature and calls your contract
  4. Your contract uses _msgSender() instead of msg.sender to get the real user

The trick? Forwarder appends the original sender (20 bytes) to calldata. Your contract extracts it:

function _msgSender() internal view returns (address sender) {
    if (msg.sender == trustedForwarder) {
        // Extract from last 20 bytes
        assembly {
            sender := shr(96, calldataload(sub(calldatasize(), 20)))
        }
    } else {
        sender = msg.sender;
    }
}

I Built a Minimal Example

I created a simple repo to demonstrate EIP-2771 with both ERC20 and ERC721:

:backhand_index_pointing_right: GitHub - letitcodedev/eip2771-example

git clone https://github.com/letitcodedev/eip2771-example
cd eip2771-example
pnpm install && pnpm test

What’s inside:

  • Forwarder.sol - Trusted forwarder with EIP-712 signatures
  • ERC2771Context.sol - The _msgSender() magic
  • GaslessToken.sol - ERC20 with meta-tx
  • GaslessNFT.sol - ERC721 with meta-tx
  • Tests showing gasless transfers in action

Use Cases

  • Onboarding - New users try your dApp without buying ETH
  • Gaming - Players focus on playing, not gas fees
  • NFT mints - Smoother mint experience
  • DAO voting - Vote without ETH in wallet

Hope this helps someone understand EIP-2771! Feel free to ask questions or open issues on the repo.