Arbitrum
Arbitrum is Ethereum's largest L2 by TVL, using optimistic rollup technology to batch transactions and inherit Ethereum's security at a fraction of the cost. It supports the full EVM opcode set, enabling seamless dApp migration. GMX pioneered on-chain perpetuals on Arbitrum, and the chain hosts a dense ecosystem of DeFi protocols including Uniswap v3, Camelot, and Radiant.