I’ve often thought of creating a tool as a side project but I can never figure out how it can be monetized. For example, looking up DNS records or prettifying JSON seem like things that will have a lot of users, but who will pay for that? How do you monetize these ideas?
1. Ads through Ethical Ads or Carbon Ads. This is what I have with nslookup. It's at $500/month on these volumes: https://plausible.io/nslookup.io
2. An exclusive ad deal with a complementary service. That's what I have with whoismyisp.org. Think about what people are working on when they visit your tool, then find a service that they'll need right after that task.
3. Donations
4. Sell a course. i.e. "DNS for developers" for nslookup.io.
5. Add a paid API. i.e. DNS lookup API for nslookup.io.
6. Add a SaaS that does something similar, but more complex. i.e. monitoring DNS records for nslookup.io.
I'm also happy to give feedback on any side project (idea) you're working on.