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.

Depending on your definition of “free” you could use Keet: https://keet.io/

https://www.archivebuttons.com/ is the way

Also: https://standardebooks.org/

Matrix is very good and flexible. If you need something that is interface-compatible with Discord, there is: https://revolt.chat/