Firebase Exploration: Note Taking App
View the live app at notes.nsim.dev.
The inspiration for this came from watching colleagues discover vibe coding. They had ideas for tools they had always wanted to build but never had the programming background to execute, and suddenly they were shipping real apps in an afternoon. That shift is genuinely exciting to see. It also raised a question worth exploring: how much can you actually secure one of these quickly built apps?
There is a pattern that keeps showing up in quick frontend projects. A hardcoded PIN guarding an admin panel, a static site pretending to have authentication. It works until it doesn't, and usually it doesn't for long. The goal here was to find out whether proper security is achievable within the same low-friction, fast-to-ship approach that makes vibe coding appealing in the first place.
I wanted to test whether Firebase's free Spark tier was enough to replace that approach with something real. The answer is yes, and the gap in effort is smaller than you would expect. Firebase Authentication handles identity, Firestore Security Rules lock data down to the authenticated user, and the whole thing is live in a few hours with Claude Code doing the heavy lifting on the implementation.
The app itself is a note taking tool, deliberately simple so the focus stays on the security layer rather than the features. Notes are stored in Firestore and scoped per user at the rules level, meaning there is no server-side code validating access. The database simply refuses to serve data to anyone who isn't the owner. Authentication state persists across sessions through Firebase's built-in token management.
The takeaway is that the Spark tier is genuinely sufficient for this kind of app. You get proper authentication, a rules-enforced database, and hosting, all without standing up any backend infrastructure. For small dynamic apps that would otherwise cut corners on security, it's a practical and accessible option. And for anyone who has been vibe coding their way to something useful, it's a pattern worth knowing.