Just to correct the info above, if you go to gofundme.com and go to their frequently asked questions section, it shows right there that they take 5% commission on all the donations (that covers the web hosting platform and their profit margin, which I think is quite reasonable). The merchant account credit card fee is another 3% (which is industry average and not at all unreasonable). That's a total of 8%. If you raise $1, 000, for example, you'd get $920.00 (total fees of $80.00).
I'm not sure how the person above came up with the idea that gofundme gets 75% of the money. It is simply not true and it's all on their site, very transparent for all to see up front. Hope this helps! It is a great site to use if you are raising money and certainly the cost is outweighed by the convenience of being able to accept credit cards.