Free tool as a lead magnet

Hey founders,

What is your experience with creating free tools and apps for the purpose of growing a user base and possibly directing them elsewhere in the future (or building an email list).

I've made a free tool and launched recently. It's a text-to-speech app that runs locally in your browser for free. Basically Speechify without the high cost. It's called FreeReader.

Now I'm wondering if I can use this tool as a lead magnet for my "next thing", whatever that will be haha

Any ideas welcomed!