From 0 to 100 users in 11 weeks with zero ad spend. Here is what actually worked.

In February I launched FluoTest, a free scored quiz tool.

Today we have 100+ users across 15+ countries and I have not spent a single euro on marketing. Here is exactly what worked and what did not.

# What I built and why

I was taking too many unqualified discovery calls. When I looked at tools that could fix this, ScoreApp wanted $1,164 a year and Typeform charged $708 just to unlock scoring. I decided to build my own and make it free.

# What actually drove growth

ChatGPT was by far the biggest channel. I never optimized for it, never tried to get listed anywhere. People just started finding FluoTest through AI recommendations. A vet in the UK, a workplace safety officer in South Africa, someone from Universal Music, a professor at CalArts. All via ChatGPT, all organically.

Google search started picking up around week 6 after I published a few comparison blog posts. Reddit drove a burst of signups in the first few weeks from two posts that did reasonably well.

# What did not work

Cold outreach on LinkedIn was a complete waste of time. DMs to ICPs got ignored almost universally. I stopped after two weeks.

# The unexpected insight

I built FluoTest for lead qualification. But people are using it for healthcare screening, workplace safety assessments, hiring, education. The actual use case is broader than I thought. Score any decision and automate what happens next turned out to be a more universal problem than qualify leads.

# What is next

Launching on Product Hunt on May 19. Curious if anyone else has experienced this kind of unexpected use case expansion early on.