Uniswap v2: What It Is, How It Works, and Why It Still Matters in 2025

When you trade crypto without a middleman, you’re likely using something built on Uniswap v2, a decentralized exchange protocol on Ethereum that lets users swap tokens directly from their wallets using automated liquidity pools. Also known as the original automated market maker, it changed how people traded crypto by removing order books and replacing them with smart contracts that automatically set prices based on supply and demand. Before Uniswap v2, you needed a centralized exchange like Binance or Coinbase to trade lesser-known tokens. Now, anyone with an Ethereum wallet could list a new token or swap it for ETH in seconds—no approval, no KYC, no waiting.

Uniswap v2 wasn’t just a trading platform—it was a new financial system. It introduced AMM, an Automated Market Maker model that uses mathematical formulas to price assets without buyers and sellers matching orders. Also known as constant product market maker, it relied on a simple rule: x * y = k. As more people bought one token, its price rose automatically. This made it possible to trade obscure tokens with tiny volumes, something centralized exchanges refused to support. And because it ran on Ethereum, the blockchain that hosts most DeFi apps and smart contracts, it became the default infrastructure for dozens of other protocols, from lending platforms to yield farms. You didn’t need to trust a company—you trusted code. That’s why so many projects still list their tokens on Uniswap v2, even though newer versions like v3 and v4 exist.

But Uniswap v2 isn’t perfect. It’s slow and expensive on Ethereum, especially during spikes in activity. That’s why many traders now use layer-2 solutions or newer DEXs like SushiSwap or Curve. Still, if you’re trading tokens that aren’t listed anywhere else, or if you’re checking the history of a project’s liquidity, you’ll still find Uniswap v2. It’s the foundation. Even if you don’t use it directly, it’s behind many of the tools you do.

Below, you’ll find real-world examples of how Uniswap v2 shaped DeFi—some projects that launched on it, others that got ripped off because of it, and a few that still rely on it today. You’ll see what went right, what went wrong, and why this version still matters more than most people think.