Uniswap Labs publishes the v4 design with hooks and a singleton pool contract

Uniswap Labs/Uniswap v4

Hayden Adams published the Uniswap v4 design as open draft code. Its 'hooks' let pools run custom code (e.g. dynamic fees or limit orders); a single 'singleton' contract holding all pools cuts pool creation gas by 99%; and 'flash accounting' settles only net balances. The code used a four-year Business Source License.

• Hooks: contracts running at lifecycle points (e.g. dynamic fees, on-chain limit orders, custom market makers).
• Singleton pool: one contract for all pools vs. separate v3 contracts, cutting pool-creation gas 99%.
• Flash accounting: transfers only net balances, not per-swap moves, improving efficiency and gas savings.
• License: Business Source License 1.1 (4-year commercial restriction, then GPL); governance/Labs can grant exceptions.