Introduction

Using Gelato Relay, we relay your user's transactions on-chain, enabling secure gasless transactions for an ultra-smooth UX for your app. This allows for a variety of new web3 experiences, as the user can now pay by only signing a message, or their transaction costs can be sponsored by the developer. As long as the gas costs are covered in one of the multiple payment methods that Gelato supports, we handle the rest reliably, quickly and securely.

Prerequisites

• "node": ">=14.0.0"
• Basic JavaScript/TypeScript knowledge.
• ethers knowledge

Getting started

1: Installation

Install the Gelato Relay SDK

yarn add @gelatonetwork/relay-sdk

2: Choose the Method

At this point, you will need to answer the following questions, which will determine the method to use when calling the Gelato Relay.

• Do you require user authentication? When the use-case requires to authenticate the original user, you will need to implement the ERC2771 method where the user will sign the payload, and the original user will be decoded on-chain from the callData replacing msg.sender through _msgSender(), please see additional info here.
• What is the funding strategy?

When relaying a transaction, Gelato Nodes cover the gas fees upfront. There are two ways to reimburse these fees:

1. SponsoredCall Method :
   • Create a 1Balance account and deposit USDC on Polygon.
   • This balance covers transaction fees across all EVM chains where Gelato is deployed.
2. SyncFee Method :
   • The transaction transfers the required fee back to Gelato while executing.
   • The target contract must inherit the "Gelato Relay Context" contract.
   • This ensures access to built-in methods for querying and transferring the fee to Gelato.

More details can be found here.

If you require user authentication and you want to pay the transactions with a 1Balance account, the method to use is the sponsoredCallERC2771.