DEX vs centralized exchange: the core difference
When you trade on Coinbase or Kraken, you deposit your crypto into their custody. They hold your funds, match buyers with sellers, and process withdrawals. If the exchange gets hacked, goes bankrupt (hello, FTX), or freezes your account, your money is at risk.
A DEX works differently. You connect your wallet, make a trade, and the tokens go directly from your wallet to the other party's wallet (or a liquidity pool). The exchange never holds your funds. You stay in control the entire time.
The trade-off is clear: centralized exchanges are easier to use, have better prices for large trades, and offer customer support. DEXs give you full control, more privacy, and access to tokens that aren't listed anywhere else. Most active crypto users end up using both.
How AMM-based DEXs work
Most DEXs don't use order books like traditional exchanges. Instead, they use Automated Market Makers (AMMs). This was the breakthrough innovation that made DEXs practical.
Here's the simple version: instead of matching buyers and sellers, AMMs use liquidity pools. A pool is a smart contract holding two tokens (like ETH and USDC). When you want to trade ETH for USDC, you trade against the pool. You put ETH in, and the pool gives you USDC based on a mathematical formula that determines the price.
The formula in the original Uniswap was elegantly simple: x * y = k. The quantity of Token A times the quantity of Token B always equals a constant. As you buy Token A from the pool (removing it), Token A's price goes up because there's less of it. Supply and demand, enforced by math.
Who puts tokens in these pools? Liquidity providers (LPs). Anyone can deposit tokens into a pool and earn a share of the trading fees. If a pool charges 0.3% per swap, that fee goes to LPs proportional to their share of the pool. This is one way people earn yield in DeFi.
The catch? LPs face impermanent loss. If the relative price of the two tokens changes significantly, the LP's position can be worth less than if they'd just held the tokens. It's the cost of providing liquidity, and it's something every LP needs to understand.
Types of DEXs
Constant product AMMs
The original model (Uniswap V2, SushiSwap). Simple, works for any token pair, but not very capital efficient. Most of the liquidity in the pool sits unused at extreme prices. Uniswap V3 improved this with concentrated liquidity, letting LPs choose specific price ranges to provide liquidity in.
Stable swap AMMs
Optimized for trading between similar assets. Curve Finance pioneered this model for swapping between stablecoins (USDC, USDT, DAI) or between different wrapped versions of the same asset (stETH/ETH). By using a different mathematical formula, these pools offer extremely low slippage for same-peg trades.
Order book DEXs
Some DEXs do use traditional order books, just on-chain. dYdX is the most prominent example. Order book DEXs offer limit orders, better pricing for large trades, and a trading experience closer to what centralized exchange users are familiar with. The challenge is that on-chain order books need very fast, cheap blockchains to be practical.
DEX aggregators
Instead of trading on a single DEX, aggregators like 1inch, Jupiter (on Solana), and Paraswap search across multiple DEXs to find you the best price. They might split your trade across several pools to minimize slippage. If you're trading any significant amount, you should almost always use an aggregator rather than going directly to a single DEX.
Intent-based DEXs
The newest evolution. Protocols like CoW Swap and UniswapX use an intent-based model where you sign a message saying what you want to trade, and professional "solvers" compete to fill your order at the best price. This can include off-chain liquidity, MEV protection, and even cross-chain trades. You don't pay gas for failed transactions, and you often get better prices than routing through AMMs directly.
Popular DEXs by chain
Every major blockchain has its dominant DEXs:
Ethereum: Uniswap (the biggest AMM by volume), Curve (stablecoin swaps), 1inch (aggregator), CoW Swap (intent-based).
Solana: Jupiter (dominant aggregator), Raydium (AMM), Orca (concentrated liquidity AMM).
Arbitrum/Base/Optimism: Uniswap V3 is available on all major L2s. Aerodrome on Base, Camelot on Arbitrum.
BNB Chain: PancakeSwap, still the most popular DEX there despite the chain being less cool than it used to be.
How to trade on a DEX
If you've never used a DEX, here's a step-by-step overview:
1. Get a wallet. You need a non-custodial wallet. MetaMask for Ethereum and L2s, Phantom for Solana. Install the browser extension or mobile app and fund it with some crypto.
2. Connect to the DEX. Go to the DEX's website (verify the URL carefully) and click "Connect Wallet." Your wallet will ask you to approve the connection.
3. Select your tokens. Choose which token you're selling and which you're buying. The DEX will show you the current exchange rate and estimated output.
4. Set slippage tolerance. This is the maximum price difference you'll accept between when you submit and when the trade executes. 0.5% is standard for major tokens. For smaller, volatile tokens you might need 1-3%.
5. Approve and swap. If it's your first time trading a token, you'll need to approve the DEX to access that token (a one-time transaction). Then confirm the swap. Your wallet will show you the gas fee.
6. Wait for confirmation. On Ethereum mainnet this takes 15-30 seconds. On L2s and Solana, it's near-instant. Once confirmed, the new tokens are in your wallet.
Risks of using DEXs
DEXs are powerful tools but they're not without risk:
Smart contract risk. If there's a bug in the DEX's code, funds can be drained. This has happened to several DEXs. Stick to audited, battle-tested protocols.
Fake tokens. Anyone can create a token and add liquidity for it on a DEX. Scammers create tokens with names identical to legitimate projects. Always verify the token's contract address before trading.
MEV and sandwich attacks. Bots can front-run your trades for profit. Use MEV protection tools like Flashbots Protect or trade on intent-based DEXs like CoW Swap.
Phishing. Fake DEX websites are common. Always bookmark the real URL and never click links from DMs or ads. Check that you're on the correct domain before connecting your wallet.
Token approvals. When you approve a token for trading, you're giving the DEX's smart contract permission to move that token from your wallet. If the contract is malicious, it could drain your tokens. Revoke old approvals using tools like Revoke.cash.
No customer support. If you send tokens to the wrong address or trade the wrong token, there's nobody to call. Transactions are final. Triple-check everything.
When to use a DEX vs a centralized exchange
Use a centralized exchange when you're buying crypto with fiat currency, trading large amounts where price impact matters, or if you want a simpler interface with customer support.
Use a DEX when you want to trade tokens that aren't listed on centralized exchanges, when you want to maintain custody of your funds, when you need access to DeFi protocols, or when privacy matters to you.
Most crypto-native users do both. They on-ramp fiat through a centralized exchange, then move to a wallet and trade on DEXs. It's not either-or.
The bottom line
DEXs let you trade crypto without trusting a centralized company. AMMs replaced order books with liquidity pools, making it possible for anyone to swap any token instantly. They come with real risks (smart contract bugs, fake tokens, MEV) but they're a fundamental piece of crypto infrastructure.
New to DeFi? Start with our DeFi guide. Want to understand the MEV problem on DEXs? Read the MEV explainer. And check the glossary for any terms you're not sure about.