Uniswap
Uniswap's VolatilePair Hook is live on Ethereum mainnet, launching with an ETH/USDC pool. Instead of one static fee, the hook sets a fee for each side of the trade and shifts both with the market, letting LPs keep more of the value they create. Developer docs for the hook are now live via Uniswap Builders.
LPs can provide liquidity now on the Uniswap Web App. VolatilePair joins StablePair, Permissioned Pools, and LitePSM in Uniswap's v4 hook lineup, with more hooks on the roadmap.