Crypto users, to doing a trading by not providing their crypto assets to the centralized authority,  DEX options are available today. It functions as a thing of the third-party crypto wallet, smart contract, liquidity pool, and automated market maker. The following features should be in the DEX platforms 

Atomic Swap Engine

Wallet Extension Integration

Liquidity Management

Not to show a fake volume in it

User control funds

When involved in building the best DEX trading platform give importance to the above things. And, deploying it to the user-expected things.