CEX (Centralized Exchange)

How a CEX works

A CEX is essentially a crypto-native version of a traditional securities exchange:

• Users deposit crypto into the exchange's wallet, which acts as custodian.
• Buy and sell orders meet on the exchange's central order book.
• The exchange's matching engine pairs orders, executes trades, and updates user balances internally.
• Withdrawals are sent on-chain when users request them.

The trade itself doesn't touch the blockchain. Buying ETH on Coinbase doesn't move ETH between wallets — it just shifts an internal database record. Only deposits and withdrawals are on-chain.

This is the structural difference from a DEX, where trades happen in smart contracts and the blockchain is the matching engine.

Major centralized exchanges

The largest as of early 2025, by volume:

• Binance — largest globally; deeply integrated with BNB Chain.
• Coinbase — largest US-based exchange. Public company. Operates Base L2.
• OKX — large Asia-focused exchange with significant derivatives volume.
• Bybit — Singapore-based, derivatives-heavy.
• Kraken — long-running US exchange with strong security track record.
• Bitget — large derivatives platform.
• Upbit — dominant Korean exchange.

Several large exchanges of past cycles have collapsed (FTX, Mt. Gox) or pulled out of major markets (Binance from the US under regulatory pressure, with Binance.US operating separately).

Why CEXes still dominate volume

Despite the rise of DEXes, centralized exchanges still handle the majority of crypto trading volume globally. A few reasons:

• Fiat ramps. Buying crypto with USD, EUR, or KRW typically requires a CEX as one leg.
• Speed and cost. A trade on a CEX is essentially free and instant from the user's perspective; on-chain swaps incur gas and have settlement times.
• Liquidity. Major pairs on top CEXes have tighter bid-ask spreads than equivalent DEX pools, especially in spot trading.
• Advanced order types and derivatives. Limit orders, stop-losses, perpetuals, options — most still live on CEXes (with notable exceptions like Hyperliquid).
• Regulatory familiarity. Institutional users typically need a custodian with a recognizable license, not a smart contract.

The custody trade-off

The fundamental drawback: when you hold crypto on a CEX, you don't actually hold it — the exchange does. If the exchange fails, gets hacked, freezes withdrawals, or absconds with funds, you're a creditor in bankruptcy. FTX users learned this in November 2022; Mt. Gox users have been working through claims since 2014.

The crypto-native rule: don't keep more on a CEX than you're actively trading or willing to lose. Long-term holdings belong in self-custody, ideally on a hardware wallet.

Proof of reserves

Following the FTX collapse, major CEXes adopted some form of proof-of-reserves disclosure: cryptographic proofs that they hold assets equal to or greater than their customer liabilities. The implementations vary in rigor — some demonstrate only assets without the corresponding liabilities, which is meaningless. Better implementations use Merkle-tree commitments to user balances paired with on-chain proof of asset holdings.

Even rigorous proof of reserves is a snapshot, not a continuous guarantee. It can be circumvented (loans of assets immediately before snapshot), and it doesn't address operational risk, governance risk, or future fraud. It's better than nothing but not a substitute for self-custody.

CEX vs. DEX trade-offs in one line

A CEX trades convenience and counterparty risk for the simplicity of a familiar product. A DEX trades self-custody and verifiability for the friction of operating a wallet and paying gas. Most active users use both, in different mixes for different purposes.