first of all , you should go to ./frontend folder and run this command :
npm install
then you should run this command also in ./backend folder.
after that , you should run the command below in ./cache folder:
go mod tidy
now , to run backend API (and connect it to cache ) , in ./cache , run this command :
go run ./main.go
and in ./backend , run this command :
npm start
and after all, you should run this command in ./frontend folder:
npm start
now , frontend is running on localhost and port : 3000 . API is also connected to frontend (and also can be used standalone) and is running on localhost and on port 8000. And caching system is also running as a standalone API on localhost and on port 8080.