I've been running a small data tool as a side project for about 14 months. It has ~400 active users now. For the first year it was completely free, and I keep getting asked why I haven't monetized it yet. Decided to think through this publicly because the answer is less obvious than most people make it sound.
The usual advice is "add a paid tier when you hit 1000 users" or "monetize when people ask to pay you." Both are too vague to be useful.
Here's the framework I'm actually using:
Keep it free if: You're still figuring out what the core value proposition actually is You have less than ~6 months of user data Your retention is weak (users come back fewer than 3-4 times in the first month) The market is winner-take-all and free growth is your moat The maintenance cost is genuinely low (mine was around $15/month in hosting)
Start charging when: Users tell you they'd pay without you asking You've had actual conversations with 20+ users about what they do with the tool Retention is solid and you understand why people stick around The maintenance cost is growing and you need the revenue to justify continuing You want to filter for serious users vs casual lurkers
For me, the retention wasn't strong enough until month 10. Once I could see that a specific cohort of power users was coming back weekly, that was the signal.
I launched a simple $8/month paid tier two months ago. Conversion rate is around 4% so far, which gives me about $130/month. Not life-changing, but it's real. More importantly, the paying users give way higher-quality feedback than free users.
One thing nobody talks about: monetizing too early can actually kill a project. I had a tool fail in 2022 partly because I added a paywall before I understood what value I was actually delivering. The churn was brutal and demoralizing.
The question I ask now: "Would I pay $X/month for this if someone else built it?" If the honest answer is no, I'm not ready.