From the ground up, assuming you already know JS and how to code regular web apps, the core of a PWA is offline first capability, so probably start with learning Workbox to create a service worker for gracefully handing ajax requests. Then, you'll need a way to store data locally, indexeddb is the best tool for that, I recommend a wrapper, either PouchDB or my favorite RxDB. The final, and easiest, part is the app manifest that contains the metadata about the app and it's resources. To start learning about PWA architecture I'd start here: https://developers.google.com/web/ilt/pwa/introduction-to-progressive-web-app-architectures then explore the above tools when actually building one. Answer from MindlessGuidence on reddit.com