We’ve worked on medium/large projects evolving any kind of bookings of hours, appointments, meeting, etc. We’ve connected the business and the customer sides with our booking system and we’ve provided real time data updating and displaying. The system is based on a microservice architecture which is able to scale without any issues in the future. The app includes web, ios and android versions written in react, java and swift. We’re using a GraphQL API server with express and mongoDB.