Building an AI Invoice Generator in a Week (Week 8 of My NanoCrafts Build Curriculum)

Week 8 of my NanoCrafts build curriculum had one goal: ship a second SaaS product fast. After spending seven weeks building Resume AI Tailor — a full-stack AI resume rewriter with Stripe, usage limits, and saved resumes — I wanted to validate that the patterns I'd built up weren't project-specific. Could I take the same stack and ship something completely different in a single week? The invoice generator was the perfect test. Small scope, clear value, real utility. Type a sentence, get a professional PDF. No spreadsheets, no templates, no friction. Here's how I built it. The NLP Parser — The Most Interesting Part Every invoice generator has a form. Client name, hours, rate, currency — you fill it in, you get a PDF. Boring. The interesting question was: what if you didn't have to? The core idea was simple. You type Invoice Acme for 10 hrs at £100/hr and the app figures out the rest. To make that work reliably, I built a two-tier parser. Tier 1 — Regex (fast path) The first tier is pure