Cross-Protocol is a novel bridging method that combines optimistic oracles, bond relays, and one-sided liquidity pools to provide decentralized instant transactions from the aggregation chain to the Ethereum mainnet.

Across collects a liquidity pool of ERC20 tokens on Ethereum to facilitate quick withdrawal of token deposits on layer 2 (L2) networks such as Optimism and Arbitrum. Deposits at layer 2 are one-way and are sent by the slow local bridge of L2 network to the pool on Ethereum to repay the liquidity provider. This can be thought of as a liquidity provider providing short-term loans on Ethereum secured by layer 2 deposits.