Across Protocol Polygon — an internet-based bridging protocol that allows users to complete transactions between chains almost instantly. This is achieved through the use of an optimistic oracle, linked relays and one-way liquidity pools.
Across Protocol Polygon allows users to move tokens between chains, using a decentralized network of relayers, who are reimbursed on the chain of their choice through a single liquidity pool.
A user, who would like to move funds from chain A to chain B, deposits the funds in a "deposit box" on chain A with instructions on where they would like to deposit their funds and the fee they are willing to pay.
Relays review these deposits and once they verify that the deposit details are correct, they immediately release the funds to the user on chain B.
There are two types of fees, associated with the Across using:
- Gas fee at the destination.
- Bridge fee.
In order for Across to deliver tokens to a user in the destination chain, the transaction must be sent on behalf of the user. The destination gas fee includes the gas costs, associated with this transaction. The fees for milestone payments themselves are broken down into two components. LP fee: a fee, paid to liquidity providers for providing passive liquidity. Relay fee: a fee, paid to encourage relayers to relay your intermediate transaction.
The LP fee depends on the size of the transaction and how much of the current liquidity is used. These fees typically range from 0.06% to 0.12% of a transaction.