The motivation to write it was to do something useful the best quality I knew how.

To continue maintaining it, it's mainly a feeling of being stuck doing it the last years. Some of the practical aspects have become a huge burden.

Internal and external motivation are quite different.

What do you mean by "practical aspects have become a huge burden"? Is it fixing bugs, adapting to changing environments, feature requests by user, communicating with your userbase, or something else?

I wanted to learn how to solve the problem. I wanted to learn a new language. I figured since I was doing it anyway I might as well do it openly.

Now I keep doing it because it starts conversations with others and I occasionally see it being used by others which is a big dopamine hit.

And did you fix a problem you had yourself or was it a problem by someone else - esp. if you used a new programming language?

Yes. I wrote a tool to assist with estimating and finding the complex portions of a codebase. It works well for the issues I have been facing.