Offline pages

Hello, I am trying to build an app out of my WordPress website using Wapppress, my issue now is that I want the app to work in offline mode, which means if the user is not connected to the Internet he/she can still see the pages they already viewed or even download all the content the first time the app opens then sync everytime; I asked the plugin developer and he told me that there is no such feature for the time being; do you think there is a certain plugin that can do so for a wordpress website? or can you direct me to the code and give me a head start? thank you