That’s called arbitrage, you swap e.g. ETH for DAI on one exchange and then swap it back from DAI to ETH on another exchange. This works because the so called DEX’s (Decentralized exchanges like Uniswap) have sometimes different exchange rates for token pairs. There is also another version of arbitrage called triangular arbitrage where you swap e.g. ETH for DAI and DAI for Link and Link back to ETH. But there are following problems:
Competition:
Lots of other users too implemented a bot that does arbitrage trading already
-> There are already open source arbitrage bots like this which also uses a Flash Loan to not risk any personal capital but if you don't understand what the bot is doing, I wouldn't recommend using it. Of course risking no capital doesn't mean not being able to lose money because you always have to pay the transaction fee even though the transaction fails.
Time:
These profitable opportunities often only last for a very short time.
-> He tracked the profitable opportunities of triangular arbitrage and showed interesting data in his YouTube video.
Gas Fees:
The current situation on Ethereum makes the most arbitrage opportunities unprofitable because the gas fees are way to high.
-> Check out the Etherscan Gas Tracker. Amongst lots of other informative data it also shows the cost for an Uniswap token swap.
Front Running:
Another big problem at Ethereum is front running which basically means that because all the unconfirmed/pending transactions are public, someone else can copy it and just put a slightly higher gas as you did. The transactions of the front runners go through first and you lose the gas fee which is as said before pretty high. The funny thing is that front runners also often get front runned and so on.
-> Check out this YouTube video showing someone trying to get front runned (spoiler: he gets front runned)
Summary: There are lots of problems with arbitrage trading and it's not quite sure if you will make money at the end. Also I would say it's impossible creating an arbitrage bot without coding, at least I don't know any tools to use.
