Centralized and decentralized exchanges compared
Compare custody, execution and responsibility before you compare fees.
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What you’ll learn
- Explain who controls the assets on each type of exchange
- Tell an order book from an automated market maker
- Add up the full cost of a trade, not just the headline fee
- Name the main ways each model can fail
A centralized exchange (CEX) is a company that holds customer assets and matches trades on its own systems. A decentralized exchange (DEX) is a set of smart contracts that lets people trade from their own wallets, with each trade settled on a blockchain. Both let you swap one asset for another. They differ in who holds the assets, who executes the trade and who can step in when something goes wrong.
Key takeaways
- On a centralized exchange, your balance is a claim on the company. On a DEX, assets stay in your wallet until you sign a transaction.
- Order books match buyers with sellers. Automated market makers price each trade against a pool of assets.
- The real cost of a trade includes spread, price impact, network fees and withdrawal charges, not only the advertised fee.
- Neither model removes risk. Exchanges can fail or freeze accounts; smart contracts can be exploited or misused.
Who holds the assets?
When you deposit to a centralized exchange, the exchange controls the private keys of the wallets that hold the funds. Your account shows a balance in the exchange’s internal ledger, and trades between customers usually update that ledger without touching a blockchain. Only a withdrawal produces an on-chain transfer to an address you control.
A DEX works differently. You connect a self-custody wallet, approve the tokens a contract may spend and sign each trade. The swap executes on-chain and the output arrives in your wallet. No company holds your balance in the meantime, but nobody can reverse a mistaken transaction or reset a lost recovery phrase either.
How trades are executed
Most centralized exchanges run a central limit order book. Buyers post bids, sellers post asks, and a matching engine pairs them by price and then by time. The engine runs on the exchange’s own servers, so trades are fast and do not pay network fees. Centralized exchanges also usually require identity checks before you can deposit or withdraw, under the rules of the countries they operate in.
Many DEXs use an automated market maker (AMM) instead. Liquidity providers deposit pairs of tokens into a pool, and a pricing formula sets the rate for each trade from the pool’s balances. Larger trades move the price further along that formula. Some DEXs run on-chain order books, and aggregators split a trade across several pools to find a better rate. The liquidity and slippage lesson works through the arithmetic.
Costs beyond the headline fee
| Cost | Centralized exchange | Decentralized exchange |
|---|---|---|
| Trading fee | Maker and taker fees set by the exchange | A pool fee paid to liquidity providers, plus any interface fee |
| Spread and price impact | Depends on order-book depth | Depends on pool size and the route |
| Network fee | Usually none on trades; charged when you withdraw | Paid in the network’s native asset on every transaction |
| Getting funds in and out | Fees and minimums vary by asset and network | No deposit step; you trade from your wallet |
The cheapest advertised fee does not always give the best result. A low-fee venue with a thin order book can cost more on a large order than a higher-fee venue with deep liquidity. Compare the amount you would actually receive for your trade size, after every charge.
What can go wrong
A centralized exchange concentrates risk in one company. It can be hacked, become insolvent, pause withdrawals or restrict accounts under its terms or local law. The collapse of FTX in November 2022 showed that a balance on an exchange screen is only as good as the exchange’s ability to honor it. Some exchanges publish proof-of-reserves reports; these are point-in-time snapshots and do not always give a complete picture of what the exchange owes.
A DEX moves the risk to code and to you. Contracts can contain bugs, token approvals can be abused by malicious contracts, fake tokens can copy a real ticker, and phishing sites can imitate a real interface. A pending swap can also be exposed to transaction reordering, known as MEV, which can worsen the price you receive.
Choosing a workflow
- Decide first who you want to hold the keys, then choose venues that fit that decision.
- On a centralized exchange, check withdrawal options, supported networks and account requirements before you deposit.
- On a DEX, confirm the token’s contract address from a primary source and read each approval before signing.
- Request a quote for your real trade size and compare the amount received, not the fee percentage.
- Keep on any venue only what you need there, and know how you would withdraw if it paused service.
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