Not sure if this counts. But I use a static site generator [1] that I wrote in Python3, to create my blog. Every time I watch a foreign language movie, I use a tool that I wrote in haskell [2] to search, download and find the perfect subtitle for that movie.
Right now I am rewriting it in Rust, with the added capability of syncing the subs in case I am not able to find the perfect subtitle. It is almost done. Now I am trying to put it online.