Almost everyone arrives at a DEX from a centralized exchange (CEX) like Coinbase, Binance or Kraken. They look similar — you trade one coin for another — but underneath they work in opposite ways.
The one difference that drives the rest
On a CEX you deposit your coins and the company holds them for you. The balance on your screen is effectively an IOU; the exchange controls the real assets. On a DEX your coins stay in your wallet and move only at the instant a trade settles on-chain. You are your own custodian.
| Centralized (CEX) | Decentralized (DEX) | |
|---|---|---|
| Custody of funds | Exchange holds them | You hold them in your wallet |
| Sign-up / KYC | Account + ID check | None — just connect a wallet |
| Buy with cash | Yes (card / bank) | Rarely — needs an on-ramp first |
| Price engine | Order book | Usually a pool (AMM) |
| Support | Help desk, password reset | None — you are on your own |
| Privacy | Tied to your identity | Pseudonymous wallet address |
| You trust… | The company | The code |
Why custody matters
"Not your keys, not your coins" is not a slogan — it is the lesson from Mt. Gox and FTX, where customers lost access to funds an exchange was meant to safeguard. A DEX removes that specific risk because no company can run off with assets it never holds. In return, you take on the risk of your own mistakes.
Which should you use?
- A CEX is often better for your first purchase with cash, very large orders, and when you want a support line.
- A DEX is often better for self-custody, tokens not listed anywhere else, and access to the wider world of DeFi.
Most people use both: a CEX as the on-ramp, then a DEX for everything on-chain.
- Leaving large balances on a CEX long-term 'because it's easier' — that reintroduces the exact custody risk a DEX avoids.
- Expecting DEX customer support or a chargeback. There is none; on-chain actions are final.
- Assuming KYC-free means consequence-free. You are still responsible for your local taxes and laws.