Turned ‘free forever’ into a growth engine - users run paid ads that show my brand

Built a free quiz tool 3 weeks ago.

One requirement: keep our "Powered by FluoTest" badge.

Users started running Instagram ads to their quizzes.

**The result:**

User pays Meta €50/month.

100+ people see his quiz.

29% complete it.

Every completion shows "Powered by FluoTest."

**He's advertising for me using his ad budget.**

3 weeks in:

• 20+ users

• 3-5 running ads to their quizzes

• ~500 brand impressions from THEIR ad spend

• My ad spend: €0

**This is better than Calendly's viral loop:**

Calendly: Organic sharing

FluoTest: Paid distribution (other people's budgets)

**The math if this scales:**

1,000 users = 150-250 ad runners (if ratio holds)

At €50/month each = €7,500-12,500/month in ads showing my brand

Cost to me: €0

**My question:**

Is this sustainable or just early luck?

What happens when they realize they're advertising for me?

Anyone built similar "users advertise for you" models?

**Other stats:**

• Position 5 out of 100+ in startup competition

• €0 marketing spend

• Comparison blog posts published (vs €708/yr competitors)

• Free forever model (no bait and switch)

Building this in public. Genuinely curious if badge virality works long-term 👊