What is a DEX (decentralized exchange)? A beginner's guide

A decentralized exchange, or DEX, is a market that runs as a program on a public blockchain instead of inside a company's systems. There is no private order book and no exchange account to fund first: you swap straight from a wallet, against a pool of coins held by a smart contract, and the trade settles on the chain. On Solana there are a lot of those pools, and ripr is a trading app that reads them and sends your trade to them.

The definition is the easy half. The useful half is knowing what happens inside a swap, and what each piece looks like on screen.

What a DEX actually is

Most of the DEXes you will meet on Solana are automated market makers. Rather than matching your order against another trader, the exchange holds a pool with two sides — the coin on one side, usually SOL or a stablecoin on the other. You put SOL in, the pool sends the coin back, and a formula decides the rate.

Three things follow from that, and they are the whole idea:

1. There is no account to deposit into. You swap from a Solana wallet, and what sits on the other side is a program rather than a counterparty.
2. Every swap is a public transaction. Your wallet signs it, a Solana block includes it, and afterwards anyone can look it up on a Solana block explorer.
3. Anyone can open a pool. Nobody vets a coin before it can be traded, which is why the checks at the end of this post matter.

ripr sits on top of that world. It can trade coins across a wide range of Solana pools, as well as coins on the bonding-curve program it runs on Solana itself, and whether a particular coin is tradable comes down to its pool.

The prices, charts and trade feeds in the app come from ripr's own data and execution layer, which decodes those Solana transactions itself. For background on the chain underneath it all, solana.com is the neutral primer.

How a swap works on a decentralized exchange

Because the price comes from the ratio between the two sides of the pool, your own trade moves it. Buying takes coin out and puts SOL in, which leaves the next buyer paying slightly more. The bigger your trade is next to the pool, the more it moves — that is price impact.

That makes liquidity — the amount sitting in the pool — the number that decides whether you can get out later as easily as you got in. Pool sizes vary enormously: a coin that has traded for years can hold a few hundred thousand dollars in its main pool, while a coin minted this morning may have very little. ripr treats that number as a floor in its screener: sort by market cap and it leaves out coins with under $5,000 of liquidity or fewer than 100 holders, unless you set your own limits.

The gap between the price you were quoted and the price you actually get is slippage, and on a DEX you set a ceiling for it. Auto slippage does that for you in ripr: it reads how much the coin moved over the last five minutes and puts your maximum somewhere between 3% and 15%, or you can set a figure yourself.

When the trade goes to a pool, that setting becomes a minimum-output limit written into the transaction, so the swap can only fill at or above the amount you agreed to. If the price moves while you are deciding, ripr re-quotes and asks you to accept the new price before anything is signed. What is slippage and how should I set it? goes further into the numbers.

What you need before your first DEX trade

Three things, and ripr hands you two of them.

1. A Solana wallet. Signing up creates one for your account automatically: no separate wallet app to install, and no recovery phrase to write down before your first trade. It belongs to your ripr account rather than to a phrase, so signing back in with the same method brings your wallet with you on any device. On the web app you can also sign up with a Solana wallet you already have.
2. Some SOL in it. Each Solana transaction pays a tiny network fee, so keep a little SOL spare. Your first buy of any coin also opens a token account with a small refundable deposit, which you get back when that account is closed. In ripr you can add money by card or Apple Pay, and in India by UPI or bank transfer, through payment providers that set and show their own fees at checkout. How do I deposit SOL? lists the routes.
3. The coin's contract address. Every Solana coin has one: a long string of letters and numbers unique to that coin. Names and tickers can be copied by anybody, the address cannot. ripr lets you search by name, ticker or the full contract address, so an address a friend sends you goes straight into search.

What happens when you buy on ripr

This is the part that looks mysterious from outside, so here it is in order — one path, the same on web, iOS and Android.

1. You open the coin's buy sheet in ripr and set an amount.
2. ripr's in-house execution layer prepares the transaction on its server.
3. The app checks that prepared transaction on your device against the amount and slippage you chose, and refuses it if anything differs. That check is about the transaction, not about whether the coin itself is any good.
4. Your own wallet signs it. ripr prepares the transaction; it does not sign it for you.
5. ripr sends the signed transaction to the network and follows it until it confirms or expires.

Then the coin page catches up: your position appears, and the price, chart and trade tape keep moving over a live streaming connection rather than waiting for a refresh. That is a DEX swap end to end — a quote, a signature, a block. How do I buy a coin? walks through the sheet itself.

What to check before you swap

A DEX will quote you any coin that has a pool, so a few checks are worth the minute they take. Start with the basics: an amount you would be relaxed about losing, the contract address taken from the project's own official account rather than a reply or a DM, and a flat no to any unsolicited "presale" link.

ripr builds part of the checking into the coin page. Before you buy, it shows warnings for known rug patterns — a creator holding liquidity that is not locked, liquidity that has already been pulled, a launch that looks coordinated — and it says plainly that not seeing a warning never means a coin is safe.

Every coin also shows how much of the supply the top 10 and top 50 holders and the creator hold, which is worth a look even on established names: a Solana coin with tens of thousands of holders can still keep roughly 44% of its supply in its ten largest wallets. On iOS and Android, the coin page also flags coins that are under review, low on liquidity or still being checked, and never labels a coin safe. When you are browsing rather than buying, the Hide warnings filter in Explore takes flagged coins out of your lists. How to spot a risky meme coin is the longer checklist.

Where to start

A DEX is three things stacked up: a pool that prices the trade, a wallet that signs it, and a public transaction that settles it. Slippage, price impact, liquidity and contract addresses are the detail of making those three work in your favour.

In ripr they come already wired together. The pool side is the coin page, the wallet side arrives with your account, and the transaction side is prepared, checked and signed from the buy sheet. Open Explore, pick something from Trending or New, read its warnings and holder split before you go near the buy button, and start small. For a tour of the app first, What is ripr? is the short version.

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Last verified 2 November 2026. This article is published by ripr, which builds an app for trading Solana coins. Nothing here is financial advice.