Optimism is more than just a single blockchain – it's a growing network of chains called the Superchain, all built on the open-source OP Stack. While OP Mainnet was the first, many prominent chains now run on the Optimism’s OP Stack, including Base (by Coinbase), Unichain (by Uniswap), Ink (by Kraken), and World Chain (by Worldcoin). The OP Stack has become the leading framework for Ethereum Layer 2 chains, powering the majority of L2 activity today.