Glossary A–Z

DEX (decentralized exchange)

A DEX is an exchange made of smart contracts. You trade straight from your wallet, usually against a pool of tokens rather than another person’s order.

By TokenTrail Editorial2 min read · 6 sources
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Quick answer

A DEX (decentralized exchange) is a blockchain app that lets you swap tokens with others on the network, without the geographical restrictions of centralized exchanges [1]. Uniswap and similar DEXs use an automated market maker: a pool of two tokens priced by the formula x × y = k [2].

Key points

  • 1You trade from your own wallet; there is no account to open.
  • 2In pool-based DEXs such as Uniswap, prices come from a pool and a formula, not an order book.
  • 3DEXs swap tokens only — you cannot pay in or cash out ordinary money.

How does a DEX work?#

Instead of matching buyers with sellers, a typical DEX holds liquidity pools: smart contracts with reserves of two tokens supplied by liquidity providers. When you swap, you trade against the pool, and the pool’s price shifts as the balance of the two tokens changes [2]. In Uniswap v2, each trade pays a 0.3% fee that goes to the pool’s providers [3].

StepValue
Fee = 0.30% × 1,0003 USDC
ETH out = 100 × 997 ÷ (300,000 + 997)≈ 0.3312 ETH
Average price paid = 1,000 ÷ 0.3312≈ 3,019.03 USDC per ETH

The average price is about 0.63% above the pool’s starting price: the 0.30% fee plus the price impact of your own trade. Bigger trades move the price more — see slippage.

How is a DEX different from a centralized exchange?#

Federal Reserve researchers list three differences: centralized exchanges can convert to and from fiat money while DEXs cannot; centralized exchanges use order books while DEXs use automated market makers; and centralized exchanges often require identity checks while DEXs run on permissionless smart contracts [4]. The flip side of “permissionless” is that anyone can create new markets at will [2], so a pool can exist for any token, including a copycat of a well-known one. Read the full guide: how decentralized exchanges work.

  • Liquidity — how easily an asset can be traded; on a DEX, the tokens sitting in pools.
  • Slippage — the gap between the quoted price and the price you get.
  • Smart contract — the code a DEX is made of.
  • CEX vs DEX — a side-by-side comparison.

Frequently asked questions#

Is a DEX safer than a centralized exchange?

It removes the risk of an exchange losing your deposits, but adds smart contract risk, fake tokens and front-running. ethereum.org notes that sandwich trading leaves users with increased slippage and worse execution [5].

Do I need to verify my identity to use a DEX?

Usually not; you connect a self-custody wallet. Uniswap describes its protocol as open for public use with no ability to selectively restrict users [2]. Local laws still apply to you.

Can a DEX trade be reversed?

No. Interactions with smart contracts are irreversible [6], so check the token and amount before you confirm.

Sources#

Grade A = primary source (regulator, protocol specification, client code, original author). Grade B = expert secondary source used for explanation only.

  1. Aethereum.org. Ethereum Glossary, 2026.
  2. AUniswap Labs (developer documentation). How Uniswap Works, 2026.
  3. AUniswap Labs (developer documentation). Pools (Uniswap v2 concepts), 2026.
  4. ABoard of Governors of the Federal Reserve System. Primary and Secondary Markets for Stablecoins (FEDS Notes), 2024.
  5. Aethereum.org. Maximal extractable value (MEV), 2026.
  6. Aethereum.org. Introduction to smart contracts, 2026.