How I passed the logged-in user’s identity from one PWA to another running on a completely separate Firebase project — without writing a single line of backend code, using only the browser’s Web Crypto API and a signed URL.
The problem: two Firebase projects, no shared state
PanelControl is an internal PWA that manages operators, calendar and chat for a commercial team. From the panel, team members need to open a separate site — let’s call it Orders — running on a completely different Firebase project.
The ask was simple: when an operator clicks “Onboarding”, the destination site must know who they are without a second login. The problem is that the two apps share neither database nor Firebase authentication.
There were three options:
