Gubbins needs to be launched, not opened directly

You're seeing this because index.html was opened on its own (a file:// page). Gubbins is a web app — it relies on JavaScript modules, a cross-origin-isolated context, and an in-browser SQLite database that simply can't load from a bare file. The good news: there are two easy ways in, so pick whichever suits you.

Easiest

Use the hosted app — no server required

Gubbins is published on the web, so you don't have to run anything locally if you'd rather not. Open it in your browser and start using it right away — or click your browser's Install icon in the address bar (on a phone, “Add to Home Screen”) to install it as a Progressive Web App that launches like a native program and works fully offline. Either way Gubbins is local-first: your data lives on your own device, not on a server.

Open Gubbins on the web

or run it locally

Make sure Node.js is installed. Gubbins needs Node.js 20 or newer. If you don't have it, grab the LTS installer from nodejs.org.
Launch it from the project folder. Double-click Run.bat, or right-click Run.ps1 and choose “Run with PowerShell”. A terminal window opens and stays open while the app is running.
First launch is slower. On the very first run it installs the app's dependencies automatically — this can take a couple of minutes. Subsequent launches start in seconds.
Your browser opens automatically. Once the local server is ready, Gubbins opens in your default browser at http://127.0.0.1:5173/Gubbins/. That tab — not this file — is the real app.
To stop it, press Ctrl + C in the terminal window (avoid the [X] button, which can leave the server running in the background).

Tip: want a production-style build instead of the fast hot-reload dev server? Run Run.bat preview — it builds the optimised, minified bundle, which loads with roughly 10× fewer requests and a small fraction of the download size of the dev server. (The hosted app above is built this way too.)

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