EIP2771

EIP-2771, Ethereum Improvement Proposal 2771, defines a standard for using a trusted forwarder to enable meta-transactions in which a contract can be called on behalf of a user while preserving the original sender’s identity. The idea is to allow third parties or relayers to sponsor gas or relay transactions without requiring users to directly send a transaction with ether.

How it works: A target contract designates one or more forwarder contracts as trusted. A user signs a request and a forwarder relays the call to the target contract, typically appending the user’s address to the end of the call data. The target contract then uses a mechanism, such as OpenZeppelin’s ERC2771Context pattern, to detect that the call originated from a trusted forwarder and to extract the true sender address. Internally, the contract treats the original user as the message sender, even though the transaction payer is the forwarder.

Usage and benefits: EIP-2771 enables gasless or sponsored transactions, improving user onboarding and UX for dApps and wallets. It allows applications to pay gas on behalf of users while maintaining standard contract logic and compatibility with existing tooling that relies on a conventional msg.sender.

Security considerations: The system relies on a correctly implemented and trusted forwarder. Contracts must verify forwarder legitimacy and use the extracted sender rather than the immediate msg.sender to avoid spoofing. Misconfigured forwarders or compromised relayers can undermine security or privacy.

Relation and adoption: EIP-2771 provides a minimal, cross-contract standard for forwarder-based meta-transactions and is complemented by libraries and patterns that implement the ERC2771Context approach for obtaining the original sender.