A centralized exchange (CEX) is a company that holds your crypto and matches buyers and sellers for you. A decentralized exchange (DEX) is a set of smart contracts that lets you swap tokens directly from your own wallet, with no company in the middle.
Both are used by millions of people, and both have trade-offs. The right choice depends on whether you value convenience and fiat on-ramps, or self-custody and access to any token. If you are buying crypto for the first time, start with our guide to buying crypto safely.
Key takeaways
- On a CEX the exchange holds your funds; on a DEX you keep your keys.
- CEXs are easier for beginners and connect to bank accounts; DEXs need a self-custody wallet.
- CEX risk: hacks, insolvency, frozen withdrawals. DEX risk: smart-contract bugs, scam tokens, user error.
- «Not your keys, not your coins» — move long-term holdings off exchanges.
How a centralized exchange works
A CEX works much like an online broker. You create an account, verify your identity (KYC), deposit euros by bank transfer or card, and buy crypto. Behind the scenes the exchange runs an order book — a list of buy and sell orders — and matches them.
When you «own» bitcoin on a CEX, you really own a claim on the exchange’s balance sheet. The coins sit in wallets controlled by the company. That is convenient (you can reset a forgotten password) but it means you are trusting the company completely.
In the EU, crypto exchanges must be authorised under the Markets in Crypto-Assets Regulation (MiCA). Check that an exchange is registered with a European regulator before you use it.
How a decentralized exchange works
Most DEXs, such as Uniswap, use an automated market maker (AMM) instead of an order book. Users called liquidity providers deposit pairs of tokens into a liquidity pool. When you trade, you swap against that pool, and a formula sets the price based on the ratio of tokens in it. Liquidity providers earn a share of the trading fees. You can read more about this model in our DeFi guide.
To use a DEX you connect a self-custody wallet such as MetaMask. You approve the trade, pay a network gas fee, and the tokens arrive in your wallet within seconds or minutes. No account, no ID check — and no one to call if something goes wrong.
CEX vs DEX at a glance
| Centralized exchange (CEX) | Decentralized exchange (DEX) | |
|---|---|---|
| Who holds your funds | The exchange | You (your wallet) |
| Account & ID check | Required | Not required |
| Buy with euros | Yes — bank transfer, card | Usually no; you need crypto first |
| Token selection | Curated list | Almost any token, including scams |
| Fees | Trading fee + withdrawal fee | Pool fee + network gas fee |
| Customer support | Yes | No |
| Main risks | Hacks, insolvency, frozen accounts | Smart-contract bugs, scam tokens, wrong approvals |
The risks of centralized exchanges
History is full of exchanges that failed with customers’ money inside. Mt. Gox, once the largest Bitcoin exchange, collapsed in 2014 after losing hundreds of thousands of bitcoins. In 2022 FTX went bankrupt, and customers’ withdrawals were frozen for years.
- Counterparty risk: if the exchange is hacked or insolvent, you may lose access to your funds.
- Account freezes: exchanges can block withdrawals for compliance reasons.
- Phishing: fake login pages and support scams target exchange users.
Reduce the risk by using regulated exchanges, enabling app-based two-factor authentication, and moving long-term holdings to your own wallet — see hot vs cold wallets.
The risks of decentralized exchanges
- Scam tokens: anyone can create a token with any name, including copies of real projects. Always check the official contract address.
- Smart-contract bugs: code can contain vulnerabilities that attackers exploit.
- Unlimited approvals: approving a malicious contract can let it drain a token from your wallet. Review and revoke approvals regularly.
- Slippage and front-running: in low-liquidity pools the final price can be much worse than quoted, and bots can trade ahead of you.
- No recovery: if you lose your seed phrase or sign a bad transaction, nobody can reverse it.
Which should you use?
- Beginners usually start on a regulated CEX to convert euros to crypto.
- Long-term holders buy on a CEX, then withdraw to a hardware wallet.
- DeFi users use DEXs to access tokens and services not available on exchanges — ideally with a separate wallet holding only what they are willing to risk.
Many people use both: a CEX as the bridge between the bank and crypto, and a DEX for on-chain activity.
Frequently asked questions
Is a DEX safer than a CEX?
Neither is automatically safer. A DEX removes the risk of an exchange going bust, but puts all responsibility for security on you and exposes you to smart-contract and scam-token risk.
Do I pay tax on DEX trades?
In most countries, including Ireland, swapping one crypto for another can be a taxable disposal whether it happens on a CEX or a DEX. Keep records and check your local tax authority’s guidance.
Why do DEX trades sometimes fail?
Common reasons are a gas fee set too low, the price moving more than your slippage tolerance allows, or insufficient balance to cover the network fee.
What does KYC mean?
Know Your Customer: identity checks that regulated financial services must carry out. Centralized exchanges require them; most DEX interfaces do not.
Next step: learn why crypto transactions cost gas, or read our guide to common crypto scams before your first on-chain trade.
