We use Activity Pro for all our bookings, memberships, events, communication, videos, blogs and more. They are also building a new platform for children, to gasify children's journey through sport. I can not recommend them enough, both the price you pay and the service you receive.
No upfront cost, no monthly fees, you pay per transaction. You get a bespoke app designed specifically for you club, coaching programme, or venue. And to top it off the Activity Pro + app for kids is free for coaches/clubs and you can also earn from it as well!
No brainer, go check them out!!!