I built an AI resume builder as a side project. Here is the stack and what broke.

I'm a junior SRE during the day. For the last few months I've spent nights and weekends building ResumeSnap, a tool that takes your experience plus a job posting and writes a resume tuned to that role in about a minute. Six people have paid for it so far. That's real money from strangers who found it on their own, and the build taught me more than any course did.

Here is how it works and where it bit me.

The stack

Next.js 16 with the App Router, TypeScript, Tailwind v4. Claude Haiku does the generation because it's cheap and fast and the output is good enough for structured resume content. Stripe Checkout handles payments. Vercel hosts it on the hobby plan. Upstash Redis stores the results.

The whole thing costs me a dollar or two a month plus API usage, and the API usage only goes up when someone pays.