I use EZFacility and have really liked it. It lets my clients book and pay for sessions online. It’s also easy for myself to go in a quickly schedule someone or set up recurring sessions. There’s a lot of customizing you can do too to meet whatever needs you have for your business.
Plus their customer service is great. Super helpful whenever I have questions.
Here’s there website in case you’re interested: https://www.ezfacility.com/industries/personal-trainer-software