I am developing sales tools app , this app uses our company’s existing website database which is in MongoDB. For online access I am using WEB API calls to get product data etc. Now I was wondering as this app will be used by sales person mostly on road. So they wont have internet connectivity all the time. I was wondering what will be the best approach to make this app available offline. Which database should I use for the device and how to syn device local database with remote database.