Is NiceHash free or paid?

Excuse me, could you please clarify for me whether NiceHash is a free service or does it require payment? I've heard some people mention that it's a platform for mining and trading cryptocurrencies, but I'm not entirely sure about the cost structure. Could you elaborate on whether there are any fees associated with using NiceHash, and if so, what those fees might be? Additionally, are there any other costs that users should be aware of when utilizing the platform? Thank you for your time and assistance.