Progressive Web Apps – Service Workers and Server-free Selfies

Developing a progressive web app for Snapchat-like selfies has led me to learn about service worker practicalities, client-side image generation and standalone app limitations. I've come unstuck by a Chromium bug and sparked a WICG discussion. Combining the things I've learned along the way with advice I've received from Google and my colleagues, I'd like to share practical tips for getting started with service workers and PWAs.