Gasless Update

Removes the primary friction point for new users by eliminating the need to:

• Acquire the blockchain's native token (e.g., ETH, MATIC) before interacting.
• Understand fluctuating gas prices and transaction fees.
• Approve multiple transactions for a single logical action (e.g., token approval + swap).

The mechanism relies on a sponsor (who provides funds) and a relayer (who broadcasts the transaction). Common implementations include:

• ERC-4337 Account Abstraction: User operations are bundled and sponsored.
• Gas Station Networks (GSN): Relayers pay for meta-transactions signed by users.
• dApp-Specific Sponsorship: Applications subsidize fees to acquire users.

1. User Signs: Creates a transaction with a zero gas price, cryptographically signing it.
2. Relayer Accepts: A relayer node receives the signed message.
3. Sponsor Pays: The relayer (or a separate sponsor) submits the transaction to the network, paying the required gas in the native token.
4. Network Processes: The blockchain validates the user's signature and the sponsor's payment, then executes the transaction.

Ideal for scenarios requiring frictionless interaction:

• Mass Adoption DApps: Games, social networks, and freemium models.
• Corporate Onboarding: Businesses paying for employee or customer transactions.
• Cross-Chain Operations: Interacting with a new chain without first bridging gas tokens.
• Recurring Subscriptions: Automated payments without manual gas top-ups.

While convenient, gasless designs introduce new trust models and attack vectors:

• Relayer Censorship: A relayer may refuse to broadcast certain transactions.
• Sponsor Drain: Poorly implemented systems can allow malicious users to drain a sponsor's funds.
• Signature Replay: Signatures must be chain-specific and include nonces to prevent reuse.
• Economic Sustainability: Sponsorship models require a clear business case or protocol incentives.

• Account Abstraction (ERC-4337): A standard enabling sponsored transactions and programmable smart contract wallets.
• Meta-Transactions: The broader category of transactions where the signer and fee payer are separate entities.
• Paymasters: In ERC-4337, the smart contract that can sponsor gas fees for user operations.
• Gas Tokens: Alternative tokens (like CHAI or GST2) historically used to hedge gas costs, now largely deprecated.

A relayer or paymaster contract pays the gas fee on behalf of the user. The user signs a meta-transaction, which is submitted by the relayer. This decouples fee payment from transaction execution, enabling seamless onboarding.

• User Signs: Creates a signed message authorizing an action.
• Relayer Submits: Forwards the signed message, pays the gas, and submits it to the network.
• Contract Verifies: A smart contract (like a paymaster) validates the signature and sponsors the gas.

Account Abstraction, standardized by ERC-4337, is the primary architecture enabling native gasless experiences. It introduces UserOperations (bundled user intents) and Paymasters.

• Paymaster: A contract that can sponsor gas for other operations, allowing for gasless transactions or paying fees in ERC-20 tokens.
• Bundler: Aggregates UserOperations, pays the gas, and submits them as a single transaction, earning a fee.

Gasless updates remove critical friction points for users and developers.

• Onboarding: New users can interact with a dApp without first acquiring the native token for gas.
• Subscription Models: Applications can absorb transaction costs as a customer service.
• Batch Operations: Developers can sponsor complex multi-step interactions (e.g., a full DeFi trade) as one seamless action.
• Improved UX: Eliminates pop-up wallet approvals for gas payments, creating a Web2-like flow.

A gasless system relies on several interconnected smart contracts and actors.

• User Operation: A pseudo-transaction object expressing user intent, defined by ERC-4337.
• Paymaster Contract: Holds funds and logic to validate and pay for gas. Can implement policies (e.g., whitelists, token payments).
• Bundler: A network actor that packages UserOperations, executes them, and collects reimbursement from paymasters.
• EntryPoint: A singleton contract that orchestrates the verification and execution loop for UserOperations.

Sponsoring gas introduces new trust and economic models that must be secured.

• Paymaster Risk: The sponsoring entity must manage liquidity and prevent exploitation (e.g., infinite loops).
• Signature Verification: Robust validation is required to prevent replay attacks and ensure only authorized actions are sponsored.
• Economic Viability: The business model for absorbing gas costs must be sustainable, often requiring off-chain agreements or subscription fees.

Gasless updates are an evolution of the meta-transaction pattern. A meta-transaction is a signed message that allows a third party to execute a transaction on the signer's behalf.

• Pre-ERC-4337: Implemented via custom relayers and contract logic (e.g., Gas Station Network).
• Post-ERC-4337: Standardized and generalized through Account Abstraction, making the pattern native and more secure.
• Key Difference: Meta-transactions are a broad pattern; gasless updates via ERC-4337 are a specific, standardized implementation.

The core technical enabler of a gasless update. A paymaster is a smart contract that holds funds and agrees to pay for a user's transaction if specific validation rules are met. Key functions include:

• validatePaymasterUserOp: Verifies the transaction request and can implement custom logic (e.g., whitelists, subscription checks).
• postOp: Executes logic after the main transaction, useful for accounting or refunds. This abstraction is central to Account Abstraction (ERC-4337) and allows for sponsored, subscription-based, or token-payment gas models.

Removing the upfront requirement for native tokens (like ETH) is a major growth driver. Use cases include:

• Fiat-Onramp DApps: New users can interact immediately after a credit card purchase, without first buying ETH for gas.
• Promotional Campaigns: Projects can sponsor gas for specific actions like minting an NFT or providing liquidity.
• Enterprise Applications: Businesses can pay for employee or customer transactions, simplifying operational costs.

Gasless updates enable advanced transaction patterns that enhance usability for power users.

• Sponsored Transactions: A project's backend signs and submits transactions, paying all costs. Common in gaming or social apps.
• Session Keys: Users pre-approve a limited set of actions (e.g., trades in a game) for a defined period. The dapp's paymaster covers the gas for these pre-authorized actions, creating a seamless, app-like experience.

Users can pay for network fees using the dapp's own token or a stablecoin instead of the chain's native currency. The paymaster contract:

1. Accepts the user's ERC-20 tokens as payment.
2. Uses its own native token balance to pay the blockchain.
3. May apply a conversion rate or fee. This reduces friction for users deeply embedded in a specific ecosystem and can be a core token utility.

Sponsoring gas introduces financial risk for the paymaster operator. Common mitigation strategies include:

• Rate Limiting & Caps: Setting maximum gas cost or transaction frequency per user.
• Whitelists: Restricting sponsored transactions to verified contracts or user addresses.
• Reputation Systems: Monitoring for spam and blacklisting malicious actors.
• Bundler Policies: Bundlers (ERC-4337 entities that submit UserOperations) often have their own policies to reject unprofitable or risky sponsored transactions.

The gasless update paradigm is formally standardized and operationalized by ERC-4337: Account Abstraction. This standard defines the key actors:

• UserOperation: A pseudo-transaction object representing a user's intent.
• Bundler: Pays the network fee and submits a bundle of UserOperations to the blockchain.
• Paymaster: The contract that reimburses the bundler, enabling gas sponsorship. This stack allows gasless logic to be implemented without consensus-layer changes, driving widespread adoption.

A meta-transaction is a signed user request that is submitted to the network by a third party, separating the signer from the fee payer. This is the foundational pattern for gasless interactions. Key components include:

• User Signature: The user signs the intent of the transaction off-chain.
• Relayer: An off-chain service that submits the signed meta-transaction and pays the gas.
• Verifying Contract: A smart contract that validates the user's signature and executes the requested logic.

Account Abstraction is an Ethereum standard that allows smart contracts to function as user accounts, enabling advanced features like gasless transactions. Through ERC-4337:

• UserOperations bundle intent.
• Bundlers act as relayers, submitting bundles and paying fees.
• Paymasters can sponsor gas fees for users, enabling true gasless experiences by using deposited funds or alternative payment tokens.

Gas sponsorship is a business model where an application (dApp) or service pays the transaction fees for its users to reduce onboarding friction. This is often implemented via:

• Paymaster Contracts: Smart contracts that conditionally cover gas costs.
• Relay Services: Infrastructure like OpenGSN (Gas Station Network) that relay meta-transactions.
• Sponsored Transactions: Common in Layer 2 networks and wallet services to promote adoption.

A relayer network is a decentralized system of nodes that accept, optionally aggregate, and submit meta-transactions to a blockchain. Key examples include:

• Gas Station Network (GSN): An open-source protocol for relaying meta-transactions.
• Bundlers in ERC-4337: Specialized relayers that bundle UserOperations. These networks manage the economic risk of front-running and ensure transaction delivery without requiring users to hold the native token for gas.

Fee delegation is a broader concept where one entity agrees to pay the transaction fee for another. It is a key primitive for gasless updates and appears in several forms:

• Explicit Signature Schemes: Protocols where the fee payer is specified in a multi-signature transaction.
• Layer 2 Solutions: Networks like Optimism and Arbitrum have native support for sponsored transactions.
• Wallet Features: Wallets like Argent and Safe have built-in modules to allow third-party fee payment.

EIP-2771 defines a standard for secure meta-transactions where a Trusted Forwarder contract verifies and relays user calls. It enables:

• Secure Context Preservation: The final contract receives the original msg.sender (the user), not the forwarder.
• Simplified Integration: Contracts only need to inherit from ERC2771Context.
• Gasless Compatibility: Works with relay services to allow users to interact without gas. This standard is often used alongside GSN.