Is Bifrost free?

Excuse me, I was reading about Bifrost and I couldn't find a clear answer. I was wondering, is Bifrost a free service or do users have to pay for it? If there are any fees involved, could you please elaborate on what they are and how they are structured? Additionally, are there any limitations or restrictions that come with using Bifrost for free, if it is indeed a free service? Thank you for your time and I appreciate any information you can provide.