The Problem
Every freelancer needs invoices. Most "free" tools aren't really free — they limit you to 5 invoices/month, require an account, or add watermarks. I wanted to build the simplest possible invoice tool with zero ongoing costs.
The Architecture
The entire application runs client-side in the browser:
- No backend — all logic runs in JavaScript
- No database — form state lives in the DOM
- No auth — no accounts to manage
- No server costs — Firebase Hosting free tier handles everything
Key Technical Decisions
PDF Generation: I used jsPDF to generate invoices client-side. The PDF is created entirely in the browser and downloaded directly — no server round-trip needed.
Offline Support: The app is a Progressive Web App (PWA) with a service worker. Once loaded, it works without an internet connection.
Privacy: Since there's no backend, user data never leaves the browser. No cookies, no tracking beyond basic Firebase Analytics.
SEO Strategy
Instead of building one page and hoping for traffic, I created dedicated landing pages for each target audience:
/freelancer-invoice-template.html/contractor-invoice-template.html/consulting-invoice-template.html/small-business-invoice-template.html/how-to-create-an-invoice.html
Each page targets specific long-tail keywords and includes FAQ schema markup for rich search results.
Monetization
The core tool is free forever. Revenue comes from a premium template pack sold on Payhip for $9. The free tool drives organic traffic; the templates convert a small percentage.
Results
- Running cost: $0/month
- Deployed in under a day
- 6 pages indexed, targeting multiple invoice-related keywords
Try It
Check it out at https://invoicefreely.web.app
Feedback welcome — what would you add or change?