Title: I built a 13-app "Zoo" using Gemini Pro 3. The constraint: I wasn't allowed to inspect the code.

Nathan Johnston — Sun, 14 Dec 2025 20:38:13 +0000

I recently decided to test the absolute limits of "Vibe Coding." I wanted to know: Can I build a robust platform of micro-applications without ever acting like a traditional engineer?

To find out, I built the AppZoo.

The Rules of the Experiment: I set a strict constraint for myself: Zero Manual Code Inspection.

If Gemini wrote a React component, I wasn't allowed to audit the syntax.

If Copilot suggested a Terraform configuration, I had to deploy it as-is.

My role was limited to "Product Manager" and "QA." I could only verify the behavior, not the implementation.

The "Blind Trust" Methodology. Since I couldn't read the code to find bugs, I had to rely on a spectrum of verification:

The Logic Check (Math): For the Dual Fuel Calculator, I built a model in a spreadsheet first to know what the answers should be. I then fed the requirements to Gemini. Surprisingly, the AI didn't just match my spreadsheet—it refined the logic, handling the temperature cutoff points with better precision than my manual model. I verified the output and trusted the code to get there.

The Vibe Check (Visuals): For the Fractal Explorer or the Video-to-GIF Converter, the test plan was experiential. If the fractal zoomed smoothly, or if the GIF rendered quickly, it passed.

The Architecture: Sandbox Security Running uninspected AI code sounds dangerous—because it is. To mitigate this, I used the AI to build a Domain Isolation Model via Terraform.

Every micro-app lives on its own subdomain (e.g., zork.appzoo..., dualfuel.appzoo...).

This leverages the browser's Same-Origin Policy. If the AI accidentally wrote a vulnerability into the Zork clone, it cannot access the cookies or LocalStorage of the main parent site.

The entire "Zoo" is 100% client-side. There is no backend to hack.

The Friction points: It wasn't magic. The AI frequently got stuck in "circular reasoning" loops, proposing the same broken fix three times in a row.

The Fix: I learned that "model switching" is the best debugger. When Gemini Pro got stuck, I’d switch Copilot to a different underlying model to snap it out of the loop.

The Result: The result is a collection of 13 working apps, ranging from practical tools (Heat Pump cost analysis) to pure toys (Infinite Zork, 3D CSS Studios).

It’s messy, it definitely has bugs I haven't found yet, but it exists.

You can enter the Zoo here: https://appzoo.natnlabs.com

Forem: Nathan Johnston

Title: I built a 13-app "Zoo" using Gemini Pro 3. The constraint: I wasn't allowed to inspect the code.