Biconomy provides different approaches to enable gasless transactions for your smart contracts.
In certain use cases, it makes sense to use a custom approach. For example, where it is important to eliminate external control, or you need to implement a standard compliant function - such as EIP 2612 permits.
We provide contracts for you to inherit this functionality in your Dapps. Tokens such as Dai and USDC (and their permit functions) can be supported in your dApp, via Biconomy, using the Custom Implementation approach.
Instead of integrating meta transaction validation logic directly into your contract - you can inherit a recipient contract that can accept validated calls from a trusted forwarder. The trusted forwarder complies with EIP 2771 and verifies signatures before calling smart contract with the original user address data appended. It makes development easier and gives you the flexibility to change the trusted forwarder address when your needs change.
Read more about EIP 2771.
If your smart contracts can not be changed or updated to support native meta transactions, you can still do meta transactions via smart contract wallet approach. Here a contract wallet is created for each end user and later all his transactions are routed via his smart contract wallet.
Biconomy supports Gnosis contract wallet integration. Checkout how you can integrate meta transactions via Gnosis smart contract wallet here.
Biconomy relayers are paying the gas fees which then are paid back by the Dapp developer at the end of the month. We plan to introduce a new automated way where developers can deposit their own gas to be used for transaction fees.