UniswapUNI

Uniswap launched in November 2018 with a deceptively simple design: liquidity pools governed by the constant-product formula x·y=k. Anyone can provide liquidity, anyone can swap, no order book required. The model unlocked permissionless market-making for the long tail of tokens that centralized exchanges wouldn’t list — and became the foundation of DeFi.

Uniswap V2 (May 2020) added direct token-to-token pools and flash swaps. V3 (May 2021) introduced concentrated liquidity, letting LPs allocate capital to specific price ranges for far higher capital efficiency. V4 (early 2025) introduced hooks — pluggable contracts that customize pool behavior — and a singleton architecture that dramatically reduces gas. Each version has been deployed across Ethereum mainnet plus all major L2s and EVM chains.

The UNI token launched in September 2020 via a retroactive airdrop to historical users, distributing 400 UNI (~$1,200 at launch, multiples higher at peaks) to every wallet that had ever interacted with the protocol. The airdrop set the template for "users own the protocol" governance distribution. UNI governance controls the Uniswap treasury (~$2B at peak) and protocol parameters; the long-running "fee switch" debate over whether to activate LP fees flowing to token holders remains the most-watched governance question in DeFi.