I launched a free tool 3 days ago — users from 5 countries, zero marketing budget

3 days ago I posted about building a free invoice generator with Next.js.
Here's what happened since:

The numbers (3 days, $0 marketing)

• 24 users from 5 countries (India, USA, Canada, Italy, Poland)
• Someone in Canada downloaded a real invoice for their business
• 84 page views, 33 deep scrolls (people actually reading)
• 4 sessions from social media (Reddit + Dev.to — thank you!)
• Google already indexed 43 out of 47 pages

What worked

1. SEO from day 1 — I built 47 static pages targeting different
   keywords. Each industry template page (freelance, contractor,
   photography) is a separate Google entry point. This is how the
   Canada user found me.

2. "See a Demo Invoice" button — one click fills the entire
   form with sample data. Users instantly see the quality without
   typing anything. This converts visitors into users.

3. Auto-detecting country — the site reads your browser timezone
   and sets your currency, tax label, and language automatically.
   The Canada user saw CAD currency without configuring anything.

What I'd do differently

• Should have added more currencies from day 1 (started with 5, now have 30+)
• Educational content below each tool helps SEO — Google ranks pages with substance, not just widgets
• Reddit removed most of my self-promotion posts — commenting on other people's posts works better

What's next

Building a calculator hub next — 15 free calculators (EMI, SIP,
mortgage, tax, BMI, currency converter). Same strategy: free
forever, no signup, beautiful UI, programmatic SEO.

The goal is 10 free tools, all earning through Google AdSense.
No paywalls, no premium tiers.

Try it

freeinvoicegen.org — would love feedback from the dev community.
What features would you add?