Who does FitSW use as their payment processor? Is there any additional charges? Chris G January 24, 2019 20:20 Follow FitSW uses www.stripe.com for their online payment processing. There are no additional charges, though stripe takes 2.9% + .30 cents for every transaction. Related articles If I purchase an upgraded plan annually (to receive the discount you offer) and I want to upgrade to a plan that includes more clients, will you only charge me the difference of the two plans? How To Create A Blog Post & Change The Web Address (Computer) Comments 0 comments Please sign in to leave a comment.