Launching a Gasless Voting Experience

Gasless voting removes a major barrier to participation by allowing users to interact with a smart contract without paying network gas fees. This is achieved through meta-transactions, where a third-party relayer submits and pays for the transaction on the user's behalf. The core mechanism involves the user signing a message containing their vote intent, which is then packaged into a valid transaction by the relayer. This pattern is essential for creating inclusive governance systems on high-fee networks like Ethereum Mainnet.

To implement this, you need three core components: a Voting Contract with logic to verify off-chain signatures, a Signature Verification Library like OpenZeppelin's EIP712, and a Relayer Service. The voting contract must inherit from EIP712 and implement a function, such as castVoteBySig, that recovers the signer's address from the submitted signature and processes their vote. The signed data must follow the EIP-712 standard for structured data signing to prevent replay attacks and ensure user clarity.

On the client side, your dApp frontend uses a library like ethers.js or viem to generate the EIP-712 signature. The process involves constructing the domain separator and typed data structure defined by your contract, then prompting the user's wallet (e.g., MetaMask) to sign it. The resulting signature, along with the voter's address and vote data, is sent to your backend relayer. It's critical to include a deadline in the signed data to prevent stale votes from being submitted later.

The relayer service, which can be a simple Node.js server, receives the signed payload. Its job is to call the castVoteBySig function on the contract, attaching the necessary gas. The relayer must validate the signature's deadline and nonce (if implemented) before broadcasting. For production, consider using a gas station network (GSN) provider like OpenGSN or building on account abstraction infra (ERC-4337) for a more robust, decentralized relayer layer.

Key security considerations include preventing replay attacks across different chains or contract instances using unique domain separators, implementing a nonce system for each voter, and carefully managing the relayer's private key and gas funds. Always audit the signature verification logic. For a complete example, review OpenZeppelin's Votes utility and the EIP-712 specification.

To build a gasless voting system, you need a foundational understanding of account abstraction (ERC-4337) and gas sponsorship. The core components are a smart account for the user (like Safe{Core} or Biconomy) and a paymaster contract that covers transaction fees. You'll also need a frontend framework (React/Next.js recommended) and a Web3 provider such as Alchemy or Infura. This setup allows voters to interact with your governance contract without holding the native chain token for gas.

First, set up your development environment. Install Node.js (v18+) and a package manager like npm or yarn. Initialize a new project and install essential libraries: wagmi or viem for Ethereum interactions, @safe-global/safe-kit for smart account integration, and your chosen paymaster SDK (e.g., Biconomy or Stackup). Configure your .env file with your RPC URL, paymaster API key, and the address of your deployed voting contract. This contract must be compatible with your paymaster's validation logic.

Next, integrate the smart account and paymaster. For example, using Safe's @safe-global/safe-kit SDK, you initialize a SafeProvider connected to your paymaster's RPC endpoint. The paymaster must be configured to sponsor transactions for specific function calls, like castVote. You will need to implement a user operation bundler to relay these sponsored transactions to the network. Test this flow on a testnet like Sepolia or Amoy before mainnet deployment to verify gas sponsorship works correctly.

Finally, build the voting interface. Your frontend should detect if a user has a smart account (via EIP-1271 signature validation) and, if not, guide them through creating one with a social login or embedded wallet. The UI must construct the gasless user operation, get paymaster approval via the SDK, and submit it to the bundler. Always include clear error handling for failed sponsorships and provide fallback options. For reference implementations, review the Safe{Core} AA Kit documentation and Biconomy's gasless guides.

Gasless voting allows users to submit votes or proposals to a blockchain without paying network transaction fees (gas). This is achieved through a meta-transaction pattern, where a user signs their vote off-chain and a relayer service submits it on their behalf, covering the gas cost. The core smart contract must implement a function like voteBySig that validates the user's signature and processes the vote, ensuring only authorized actions are executed. This decouples the signer from the payer, a fundamental shift from standard Ethereum transactions.

The security model relies on signature verification and nonce management. Each vote must include a unique nonce to prevent replay attacks, where the same signed message could be submitted multiple times. The contract uses the ecrecover function (or a more secure library like OpenZeppelin's ECDSA) to reconstruct the signer's address from the signature and vote data. It then checks permissions, such as token balance for snapshot-based voting, before applying the vote. Proper implementation is critical to prevent signature malleability and front-running vulnerabilities.

A relayer infrastructure is required to broadcast signed messages. This can be a centralized service, a decentralized network like the Gelato Network or Biconomy, or a community-funded pool. The relayer monitors for valid signed messages, batches them if possible for efficiency, and submits them in a single transaction. It's essential to implement gas price policies and spam protection to prevent abuse. For production systems, consider using established SDKs like OpenZeppelin Defender to manage relayers and automate these tasks securely.

To implement this, start with a voting contract that inherits from OpenZeppelin's ERC20Votes or ERC721Votes for snapshot functionality and EIP-712 for structured data signing. EIP-712 provides a standard for typed data signatures, improving user experience and security by making the signed data human-readable in wallets. The contract must override the _delegate or custom vote function to support the signature-based pathway. Testing is paramount; use foundry or hardhat to simulate relayers and test signature generation across different signers and nonces.

User experience is dramatically improved by integrating with wallet providers. Using the EIP-712 standard, wallets like MetaMask can display a clear, structured message for signing. Front-end applications should generate the signature using libraries like ethers.js or viem, then post the signed payload to a relayer endpoint or a backend service that forwards it. For a complete gasless stack, combine this with account abstraction (ERC-4337) using paymasters, which can sponsor gas for a user's entire operation, not just a single vote, for a more seamless experience.

EIP-712, or Typed Structured Data Hashing and Signing, moves beyond signing raw hexadecimal strings. Instead, it allows users to sign a human-readable JSON structure that clearly defines the data being approved. This is a major security and UX improvement for gasless applications. In a voting context, a user signs a structured message containing the proposal ID, their chosen vote (e.g., 1 for 'Yes'), and a nonce, rather than an opaque hash. Wallets like MetaMask display this data in a readable format, significantly reducing the risk of signature phishing.

The core of EIP-712 is defining a type-specific schema and computing a hash according to the standard. This involves creating a domain separator—a unique identifier for your dApp—and the structured data itself. The domain includes the contract name ("GaslessVoting"), version ("1"), chain ID (e.g., 1 for Ethereum Mainnet), verifying contract address, and a salt. This domain binds the signature to your specific contract on a specific network, preventing replay attacks across different chains or applications.

Here is a simplified example of defining the data types for a vote in Solidity and JavaScript. The Solidity struct must mirror the structure used to generate the signature off-chain.

solidityCopy
// Solidity struct for the vote message
struct Vote {
    uint256 proposalId;
    uint8 choice; // e.g., 1=For, 2=Against, 3=Abstain
    uint256 nonce;
}

javascriptCopy
// JavaScript object for EIP-712 domain and types
const domain = {
  name: 'GaslessVoting',
  version: '1',
  chainId: 1, // Sepolia testnet ID
  verifyingContract: '0x...',
};

const types = {
  Vote: [
    { name: 'proposalId', type: 'uint256' },
    { name: 'choice', type: 'uint8' },
    { name: 'nonce', type: 'uint256' },
  ],
};

const message = {
  proposalId: 42,
  choice: 1,
  nonce: 5,
};

To generate a signature, you use a library like ethers.js or viem. The library hashes the domain separator and the typed data together, then prompts the user's wallet to sign this hash. The resulting signature, along with the original message data, is sent to your backend or directly to a relayer. The smart contract can then use the ecrecover opcode to verify that the signature corresponds to the signer's address and the hashed data, all without the user paying gas.

Implementing EIP-712 correctly requires attention to detail. Ensure the chain ID is accurate, as a mismatch will cause verification to fail. The nonce in the message is crucial for preventing replay attacks within your system; the contract must check and increment a nonce for each user. Always use established libraries for hashing and avoid rolling your own cryptographic functions. For reference, review the official EIP-712 specification and OpenZeppelin's EIP712 contract utility.

With EIP-712 signatures implemented, you have the foundational component for gasless voting. Users can securely authorize their votes off-chain with full transparency. The next step involves building a system to collect these signed messages and submit them to the blockchain, typically via a relayer that covers the gas costs, which we will cover in the following section.

The meta-transaction contract acts as a relayer that accepts signed messages from users and submits the corresponding transactions on their behalf. We'll build a GaslessVoting contract using Solidity and OpenZeppelin's EIP712 and ERC2771Context libraries. The contract must verify the user's signature, check their voting eligibility, record their vote, and pay the relayer for the gas used. This decouples the act of voting from the need to hold the chain's native token.

The contract's primary function is castVoteBySig. It takes the user's vote choice, a nonce to prevent replay attacks, and an EIP-712 compliant signature. The signature is generated off-chain by the user's wallet, signing a structured data hash that includes the contract address, the user's address, the vote data, and the nonce. The contract uses EIP712.recover to validate this signature, ensuring the vote request is authentic and authorized.

After signature verification, the contract logic mirrors a standard voting mechanism: it checks the user is registered, ensures they haven't voted before, and tallies the vote. Crucially, it uses _msgSender() from ERC2771Context, which returns the actual user address from the meta-transaction data, not the relayer's address. This preserves access control and ensures only the intended user's voting power is used. The relayer's address is available via msg.sender for potential gas reimbursement logic.

To prevent double-spending of signatures, the contract maintains a mapping of used nonces. Each successful execution increments the user's nonce. A common pattern is to use a user's current nonce from a public mapping, which the frontend can query to construct the correct signed message. The contract should also include a way for a trusted relayer to withdraw accumulated fees, if your design includes a paymaster model to sponsor the transactions.

A relayer service is a backend server that receives signed, but not broadcast, transactions from users and submits them to the blockchain, paying the gas fee on their behalf. This is the core mechanism that enables gasless voting. Users sign a transaction with their private key, proving their intent, but the relayer's wallet provides the ETH or native token required for gas. This architecture separates authorization (the user's signature) from execution (the relayer's gas payment).

To build a relayer, you need a server with a funded wallet. A common pattern uses Express.js for the API and Ethers.js or Viem for blockchain interaction. The server exposes a POST endpoint (e.g., /relay) that accepts a signed transaction payload. Critical steps include: validating the user's signature to prevent spam, estimating gas to ensure sufficient funds, and finally broadcasting the transaction using the relayer's provider. Security is paramount; implement rate limiting and, for production, consider using a transaction manager like Gelato or OpenZeppelin Defender.

Here is a simplified code snippet for a basic relayer endpoint using Ethers v6:

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app.post('/relay', async (req, res) => {
  const { signedTx } = req.body;
  try {
    // Parse the signed transaction
    const tx = ethers.Transaction.from(signedTx);
    // Verify the sender recovered from the signature
    if (tx.from !== expectedSender) {
      return res.status(400).json({ error: 'Invalid signature' });
    }
    // Send the transaction using the relayer's signer
    const txResponse = await relayerSigner.sendTransaction(tx);
    res.json({ hash: txResponse.hash });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

For a voting application, the signed transaction will typically be a call to your smart contract's vote function. The relayer must be configured with the correct RPC URL (e.g., from Alchemy or Infura) and have its wallet seeded with enough ETH on the target network (like Sepolia for testing). Always run the relayer in a secure environment, using environment variables for the private key and RPC URL. Monitor gas prices and set a max fee per transaction to control operational costs.

After deployment, integrate the relayer with your frontend. The voting UI should use a library like Wagmi or Ethers to create the unsigned transaction object, prompt the user to sign it with their wallet (e.g., MetaMask), and then POST the resulting signed transaction to your relayer endpoint. The frontend receives the transaction hash in response, which it can use to display a link to a block explorer like Etherscan. This completes the gasless flow: user intent is captured and signed client-side, but execution and cost are handled server-side by your relayer service.

With your proposal created and your voting strategy configured, the final step is to build the user interface where token holders can cast their votes. Snapshot provides a flexible GraphQL API and a client-side SDK (@snapshot-labs/snapshot.js) to integrate voting directly into your dApp or website. This allows you to create a seamless, branded voting experience without requiring users to leave your platform. The core interaction involves fetching active proposals, displaying voting options, and submitting signed messages that represent a user's vote, all without paying gas fees.

To begin, install the Snapshot client library in your project: npm install @snapshot-labs/snapshot.js. The key object you'll work with is the SnapshotClient. Initialize it with a provider, such as window.ethereum for a browser extension, to enable message signing. The primary methods you'll use are client.getProposal to fetch proposal details and client.vote to submit a ballot. A vote is not a blockchain transaction; it's a EIP-712 signed message containing the voter's address, the proposal ID, their choice, and the space ID, which is sent to Snapshot's centralized hub.

Here is a basic code example for submitting a vote using the SDK:

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import { SnapshotClient } from '@snapshot-labs/snapshot.js';
const client = new SnapshotClient();
const hub = 'https://hub.snapshot.org'; // Default hub URL

const votePayload = {
  space: 'your-space.eth', // Your Snapshot space ID
  proposal: '0x123...', // The proposal ID from Step 3
  type: 'single-choice', // Or 'approval', 'quadratic', etc.
  choice: 1, // The index of the selected option (e.g., 1 for 'Yes')
  metadata: JSON.stringify({})
};

// The client handles signing with the connected wallet
const receipt = await client.vote(window.ethereum, address, votePayload);
console.log('Vote IPFS hash:', receipt.id);

After submission, the vote is pinned to IPFS and indexed by the Snapshot hub. You can verify it appears on the official Snapshot interface for your space.

For a complete voting interface, you must also handle state loading and validation. Use the GraphQL API endpoint at https://hub.snapshot.org/graphql to query for a list of active proposals in your space, their voting strategies, and current results. It's critical to validate a user's voting power client-side before allowing a vote submission. Use the client.getVotingPower method, passing the voter's address, the proposal ID, and the space ID. This method checks all configured strategies (e.g., ERC-20 balance, delegation) and returns the total power at the proposal's snapshot block.

Best practices for integration include caching proposal data to reduce API calls, clearly displaying voting deadlines and power, and providing immediate feedback after vote submission. Remember that while voting is gasless, users must still sign a message with their wallet, which is a free operation. Always link to the canonical proposal on snapshot.org for transparency, allowing users to verify results independently. Your integration is now complete, providing a secure, cost-free governance layer powered by Snapshot's off-chain infrastructure.

This tutorial demonstrated how to abstract gas fees from end-users, a critical UX improvement for blockchain applications. By leveraging Chainscore's Gasless API and sponsored transactions, you integrated a system where voting actions are submitted as meta-transactions. The sponsor (your application's backend) pays the gas, while users sign messages with their wallets, preserving security and decentralization. This pattern is applicable beyond voting to any on-chain interaction where reducing friction is a priority, such as NFT minting, governance proposals, or social interactions.

The implementation involved several key components: a Next.js frontend for the user interface, a Node.js backend with Express to sponsor transactions, and the Chainscore SDK to facilitate gasless operations. You configured a GaslessPaymaster policy, set up secure API endpoints for sponsoring transactions, and connected a smart wallet like Safe{Wallet} or ZeroDev to act as the transaction executor. Remember to manage your sponsor's gas budget carefully and implement rate-limiting or sybil resistance in a production environment.

For next steps, consider enhancing your application. Implement transaction bundling to allow users to vote on multiple proposals in a single gasless transaction, improving efficiency. Explore account abstraction features to enable social logins or session keys for repeated interactions. You can also add real-time updates using the Chainscore SDK to listen for on-chain events and refresh the UI when votes are cast. Review the Chainscore Documentation for advanced features like gas policy simulation and multi-chain support.

To deploy this application, ensure your backend environment variables (like CHAINSCORE_API_KEY and SPONSOR_PRIVATE_KEY) are securely managed using a service like AWS Secrets Manager or Google Cloud Secret Manager. Use a production-grade RPC provider for reliable node access. Finally, conduct thorough testing on a testnet, monitoring gas sponsorship costs and transaction success rates before launching on mainnet. This foundation enables you to build more complex, user-friendly decentralized applications.