Tellico is a general collection database for many things (books, movies, shows) and keeps track of many kinds of status (watched, borrowed etc.).

https://tellico-project.org/

OneLook. It’s a meta-dictionary that lists other dictionaries which have the word. It also has a reverse lookup and pattern search which I frequently use.

https://onelook.com/

I don’t know much about them to be honest, these were just the apps people were talking about

https://play.google.com/store/apps/details?id=com.google.android.safetycore

https://play.google.com/store/apps/details?id=com.google.android.contactkeys

I think Nim is the frontrunner here. Close to Python to write because it is so expressive, close to C speed because it is compiled properly.