DEX FAQ — Fees, Safety, Anonymity, and How Trades Are Priced

How does a DEX set prices without an order book?

Most use an automated market maker. A pool holds two tokens, and a formula computes your price from the pool's balances — commonly the constant product rule x × y = k, where the product of the reserves must not decrease.

Because price is a function of reserves, your trade moves the price along a curve. That movement is price impact, and it is arithmetic you can compute before trading rather than a quote from a counterparty. See how decentralized exchanges work.

What does a swap actually cost?

Three separate things:

total = swap fee + price impact + gas

The swap fee is a fixed percentage, commonly around 0.30%. Price impact depends on your size relative to pool reserves and is the component you control. Gas depends on network congestion, not trade size, so it dominates small trades.

Comparing venues on the swap fee alone misses most of what you pay.

Are DEXs safer than centralized exchanges?

Neither is categorically safer — they relocate risk.

A DEX removes counterparty risk: no operator can be hacked, become insolvent, or freeze your account. It replaces that with smart-contract risk, malicious-approval risk, irreversible mistakes, and the fact that nobody vetted the token you are buying.

The right question is which failure mode you are equipped to prevent. See DEX vs centralized exchange.

Can a DEX be hacked?

The contracts can contain exploitable flaws, and protocols have lost substantial funds that way. The front-end website can also be compromised or cloned while the contracts remain untouched.

What generally cannot happen is the operator absconding with deposits, because there are no deposits — funds stay in your wallet until you sign.

Are DEX trades anonymous?

No. They are pseudonymous, which is different.

There is usually no identity check, but every trade is permanently recorded on a public blockchain and linked to your address. Anyone can view the full history of that address, and analysis routinely links addresses to real identities through exchange deposits, reused addresses, and timing.

Treat on-chain activity as public and permanent, not private.

What happens if the DEX website goes offline?

The contracts continue to exist and function. In principle you can interact with them directly, and other interfaces may serve the same protocol.

In practice most people cannot use a contract without an interface, so "the protocol cannot be shut down" is true of the contracts and much weaker as a statement about the service you actually use. See what is a DEX.

Why did my swap fail, and why was I still charged?

A failed transaction still consumes gas — the work was performed and the state reverted, so the fee is not refunded.

The usual cause is the price moving past your slippage tolerance, which means the protection worked: you paid a fee instead of taking a bad fill. Other causes are an insufficient gas limit or a token with unusual transfer behaviour.

Do I need the chain's native token to trade?

Yes. Gas is paid in the chain's native asset, so you need some even to move a token you already hold.

Holding a wallet full of tokens and no native asset — unable to move any of them — is a routine and entirely avoidable situation.

Can I get my funds back if I send to the wrong address?

Almost never. Blockchain transactions are irreversible and there is no operator with authority to reverse one.

If you sent to an address you control on another chain, the same private key may give access there. Otherwise, treat it as permanent. Verify the middle of an address, not just the first and last few characters, and send a test transaction for anything significant.

Is a token on a DEX vetted in any way?

No. Listing is permissionless — anyone can create a pool for any token, including one impersonating an established project.

The verification a centralized exchange performs transfers entirely to you. See how to verify a smart contract.

Decentralized Exchanges — Frequently Asked Questions