Sounder is a liquidity measurement tool for Robinhood Chain (chain ID 4663). It reads pool state directly from the chain and reports how much each venue can actually absorb at a given order size, rather than the headline price a pool quotes for a trade of negligible size. Sounder supports four pool geometries: Uniswap v3, Uniswap v4 (read from the singleton's raw storage, since v4 pools have no contract of their own), Algebra-style pools, and constant product pools. For each venue it replays that pool's own swap arithmetic tick by tick to find the point at which the pool stops absorbing, and reports the resulting fill cost in basis points including fees, price impact and gas. Gas is measured from the receipts of real swaps on the chain rather than estimated. The project also publishes two contracts of its own: SounderLens, a view-only contract that returns pool readings and the correctly composed swap fee, and SounderExecutor, which enforces a minimum output by measuring its own balance before and after a trade and reverting if the trade came up short.