HSTS and Service Workers: Practical Reference Guide
HSTS and service workers overlap in ways that bite teams during deployment, local testing, and incident response. The short version: HSTS tells the browser to always use HTTPS for a host. Service workers only work in secure contexts, with a few localhost exceptions. If you get your HTTPS and redirect behavior wrong, service worker registration gets flaky fast. If you get HSTS wrong, rollback gets painful because browsers cache the policy. I’ve seen teams debug “random” service worker failures that were really bad TLS, mixed hostnames, or a stale HSTS policy. This guide is the practical version. ...