Is Uniswap free?

I'm curious to know, is using Uniswap truly free of charge? I understand that it's a decentralized exchange, but do users have to pay any fees when they swap tokens or make trades on the platform? Are there any hidden costs or expenses that traders should be aware of before diving into the world of Uniswap? Clarifying this point would greatly help me in my decision-making process when considering Uniswap as a potential trading option.