I built an AI Chrome extension with zero backend cost — here's the exact architecture

You want to add AI to your Chrome extension.

The obvious path: spin up a Node.js server, hold a master API key, charge users monthly, eat the AI cost. That's what everyone does.

I didn't do that. I built three Chrome extensions with AI features — PR summarization, risk scoring, draft review generation — and my monthly infrastructure bill is $0. No server. No backend. No API key to protect.

Here's the exact architecture, the real trade-offs, and the specific places where this approach breaks down so you don't find out the hard way.

The problem with the "standard" approach