What are you building? How much does it cost you to operate? How long do you plan to keep it free?
Do you have a monetization plan later, or is the goal something else (learning, community, portfolio, etc.)?
Would love to hear about your projects and how you think about sustainability.
It runs completely on the user's computer so there is no service to maintain.
It is a new kind of data management system that was originally an object store to replace conventional file systems; but the tagging features I designed made it useful for creating, querying, and analyzing relational tables.
It is a hobby, so I like seeing how much faster I can perform operations than regular RDBMSs. It is extremely flexible, so lately I have been testing it out using large data sets. Creating tables with 100,000 columns or doing a pivot table in a 227M row table is fun for me.
See my profile for links.
To keep costs down, I manage my own VPS and limit myself to projects that can run 100% client-side (e.g. no reliance on third-party APIs).
Because we use it (and depend on it), I am vested in making sure it works and continues to work well, and doesn't get too complex or complicated, unnecessarily.
That being said, I've made some money from donations, grants, and people paying me to manage instances for them, for example.