What is a CEX?
A CEX (Centralized Exchange) is a cryptocurrency trading platform where a central company — like Binance, Coinbase, or Kraken — holds custody of user funds and facilitates trading through an order book matching engine.
CEXs operate similarly to traditional stock exchanges: they maintain order books, match buyers and sellers, charge trading fees, and enforce KYC/AML requirements. The key trade-off is convenience versus self-custody.
CEX vs. DEX
| Feature | CEX | DEX |
|---|---|---|
| Custody | Exchange holds your funds | You hold your own funds |
| Identity | KYC required (usually) | Permissionless |
| Speed | Fast (off-chain matching) | Slower (on-chain settlement) |
| Liquidity | Usually deeper | Can be thinner |
| Counterparty risk | High (exchange can fail) | Low (no intermediary) |
| Fiat on-ramp | Yes | Usually no |
| Trading pairs | Many (including fiat) | Crypto-only |
How a CEX Works
- Registration: User creates an account and completes identity verification (KYC)
- Deposit: User deposits crypto or fiat into exchange-controlled wallets
- Trading: User places buy/sell orders; the exchange matches them off-chain
- Withdrawal: User requests withdrawal; the exchange sends funds to the user’s external wallet
During steps 2-4, the exchange holds your funds. If the exchange becomes insolvent or malicious, you may lose everything.
Custody Risk: “Not Your Keys, Not Your Coins”
When you deposit funds on a CEX, you receive an IOU — a database entry showing your balance. You don’t control the actual blockchain assets until you withdraw. This is why the phrase “not your keys, not your coins” exists.
Major exchange failures:
- Mt. Gox (2014): $450M lost
- FTX (2022): $8+ billion in customer funds missing
- Celsius (2022): $4.7 billion in user assets frozen
When to Use a CEX vs. DEX
Use a CEX when:
- You need to convert fiat to crypto
- You want fast, high-volume trading
- You need advanced order types (limit, stop-loss, margin)
Use a DEX when:
- You want full custody of your assets
- You value privacy (no KYC)
- You want to trade new tokens not listed on CEXs
Frequently Asked Questions
Q: Is it safe to keep my crypto on a CEX? A: Short-term, yes — reputable CEXs have security measures. Long-term, no — history shows that even top exchanges can fail. Best practice: only keep funds on a CEX that you’re actively trading, and withdraw the rest to a hardware wallet.
Q: What happens if a CEX goes bankrupt? A: You become an unsecured creditor in bankruptcy proceedings. Recovery typically takes years and you may receive only a fraction of your assets. This is what happened with Mt. Gox and FTX.
Q: Do CEXs report to tax authorities? A: Yes, in most jurisdictions. Major CEXs comply with local tax reporting requirements (e.g., 1099 forms in the US, CRS reporting internationally). DEXs do not, since they don’t collect identity information.