It is or was used by some companies in Munich (funkwerk) and a few others. Companies like ebay and netflix have some projects in D. The users are mostly C++ veterans so the forums are full of experienced ppl who can help. I used it heavily in my work for local scripting tasks and even write a small GUI app for our API. Used it mainly instead of Python. It’s basically a safe C with a rich stdlib. There is almost zero syntax overhead and hence if you know C, you should be fluent with D in short time. It is a pragmatic language with some nice functional syntax sugar that makes Scala cry. But the language and the ecosystem struggles with the lack of ppl and overall direction. Contributors tend to complain about long times and endless PR discussions. Some D contribs moved eventually to Rust or Go, which is sad but here we are. I think D deserves more attention than it got and continues to get.