Unity Code Generator
This is a Unity project that has a bunch of script which generates boilerplate string definitions like tags, layers, sortings layers, and so on.
Editor scripts poll modifications periodically, so you don't need to do work something for it. (auto-generated code will be stored at Assets/Scripts/AutoGenerated/* by default)
If you want auto-generations to be triggered explicitly, you can do that by deleting auto-generated .cs script.
MIT.