What Is a DEX? How Decentralised Exchanges Actually Work

If you've bought a memecoin, you've used a decentralised exchange. Uniswap, PancakeSwap, PumpSwap, Raydium — different names, same underlying mechanism.

Worth understanding, because it explains several things that otherwise look arbitrary: why your fill differs from the price you saw, why some tokens can't be sold in size, and why the whole market can exist without anyone running an exchange.

What a DEX isn't

It isn't a company holding your money. There's no account, no deposit, no signup, no KYC on most of them, and no order book matching buyers to sellers.

You connect a wallet, sign a transaction, and the tokens move. Nobody holds anything on your behalf at any point.

That's the significant part. A centralised exchange takes custody of your funds and matches you against another user. A DEX does neither — it executes a swap against a pool of tokens sitting in a smart contract.

The pool, and the formula

Almost every DEX you'll use runs an automated market maker.

Someone creates a pool by depositing two assets — say a token and SOL — in some ratio. The contract holds both. When you buy the token, you're putting SOL into that pool and taking tokens out. The pool's formula recalculates the price based on the new balance.

There's no seller on the other side. There's a pool, a formula, and your transaction.

The formula's job is to make sure the pool never runs empty. As you buy more of a token, each subsequent unit costs more, so the pool always has something left. That's why large buys push the price up as they execute rather than filling at a single price — the mechanism is doing exactly what it's designed to do.

Why this explains your fill

Two consequences follow directly, and between them they account for most of the difference between the price you saw and the price you got.

Price impact. Your own trade moves the pool. On a deep pool that's negligible. On a thin one, buying meaningfully moves the price against you as you go, and every token you buy costs more than the last. That's not a fee, it's the arithmetic of the pool, and no setting protects you from it. It's the practical reason liquidity matters more than market cap.

Slippage. Between submitting your transaction and it confirming, other people trade the same pool. The price you'll get isn't the price you saw. Your slippage tolerance is you telling the network how much of that movement you'll accept before the trade cancels.

Both come out of your position and neither appears as a line item anywhere.

Who provides the liquidity, and why

Anyone can deposit into a pool. Liquidity providers earn a share of the trading fees in return, proportional to their share of the pool.

Which is why liquidity exists at all for tokens nobody has ever heard of — someone stands to earn fees from the trading. It's also why "liquidity locked" and "liquidity burned" matter so much. LP tokens represent a claim on the pool, and whoever holds them can withdraw the underlying. If nobody can withdraw it, the pool can't be pulled from under you.

The thing nobody mentions to new LPs: providing liquidity on a volatile token frequently loses money relative to just holding it, because the pool automatically sells the asset that's rising and buys the one that's falling. Fees can offset that. On a memecoin they often don't.

Where DEXs beat centralised exchanges

Anything can list. No approval process, no listing fee, no gatekeeper. That's how a token can exist and trade within thirty seconds of someone deciding to make it — and it's why every memecoin starts life on a DEX rather than an exchange.

You keep custody. Your funds are in your wallet until the moment of the trade. Nothing to freeze, nothing to withdraw, no platform that can pause trading on you.

It's permissionless. No account, no region check at the protocol level, no approval.

Where they're worse

No recourse. Wrong address, wrong token, wrong network — there's nobody to email. The transaction executed as instructed and instructions are final.

Anything can list. The same feature, from the other side. A DEX has no view on whether a token is a scam, and listing means nothing about legitimacy — which is why the rug pull checks exist.

Your transaction is visible before it confirms. On most chains, pending transactions sit in a public mempool where bots can read them. That's the basis of sandwich attacks, and it's a structural feature of transparency rather than a flaw anyone can patch.

Gas costs on every action. Including failed transactions, which you pay for regardless.

Aggregators and routers

You'll see references to routing — Jupiter on Solana, various aggregators on EVM chains.

The same token often exists in several pools across different DEXs, each with its own liquidity and therefore its own price. An aggregator checks them all and can split a trade across multiple pools to reduce price impact.

For anything larger than a small position, routing matters. A trade that would move one pool badly might barely register when split across four.

How this connects to what you're actually doing

A trading bot is a layer over the same infrastructure. When you paste a contract into Telegram and press buy, the bot is constructing and submitting a DEX swap from your wallet. It isn't an exchange either.

What the bot adds is everything around the transaction — presets, order types, protection, and the ability to act without opening anything. The swap itself is identical.

Axxel runs on Ethereum, Base, BSC, Solana and Robinhood Chain with market, limit, trailing and sniper orders, MEV protection, and configurable slippage and tax limits. Flat 0.9%, non-custodial, no subscription.

Understanding the pool underneath is what turns "my fill was bad" into "I bought too much into too thin a pool with too much slippage tolerance." Same outcome, but the second version is fixable.

Crypto trading carries risk. Most memecoins lose value. Nothing here is financial advice. Axxel is not available in all regions.