How do you build your system? Microservices or monolith? Microkernel architecture, hexagonal, layered, event driven, reactive?
Did you chose technology? Maybe Java 8, 11, Latest, Scala, Kotlin, Groovie, Rubby, Python, .Net?
How they communicate each other? Http/REST/WebServices, MQ, Kafka, Akka, Database?
Do you need frontend? Angular.Js, React.Js, Vue.Js, Polymer.Js, Vaadin, Swing, JavaFX?
Mobile? Android or iOS? Cross-platform or native?