What do the "Other" and "Developer" options in Spotlight index? In Spotlight, you can set what types of items you want to be indexed and searchable.  Most of the options are fairly straightforward: "Contacts" searches your contacts, "Images" for images, and so on.  However, there are two options that I don't understand: "Other" and "Developer".



The Search Results panel is rather fine grained.  Why is there, what I'm guessing to be, a catch all option with "Other" and what does it catch?  Similarly, what does the "Developer" option index?

I looked in the "Spotlight preferences" page of the "Mac Help", but from what I can tell, it doesn't detail it.  In fact the "Narrow the scope of your searches" topic details everything but those two options under the "Search by the type of items" section:

Type of item        Keyword
-----------------------------------------
Apps                kind:application
                    kind:applications
                    kind:app

Contacts            kind:contact
                    kind:contacts

Folders             kind:folder
                    kind:folders

Email               kind:email
                    kind:emails
                    kind:mail message
                    kind:mail messages

Calendar events     kind:event
                    kind:events

Reminders           kind:reminder
                    kind:reminders

Images              kind:image
                    kind:images

Movies              kind:movie
                    kind:movies

Music               kind:music

Audio               kind:audio

PDF                 kind:pdf
                    kind:pdfs

Preferences         kind:system preferences
                    kind:preferences

Bookmarks           kind:bookmark
                    kind:bookmarks

Fonts               kind:font
                    kind:fonts

Presentations       kind:presentation
                    kind:presentations
This is sort of a half answer, half response containing observations and guesses in response to bmike's comment.

It looks like the "Developer" option is for files that macOS considers to be development related files.  For example, I searched for .h, .html and .m files and they were listed under the "Development" category:



"Other" must be for anything that macOS can't make a good guess at.  For example, I searched for .json files and actual .json files showed up under "Developer".  However, files that had unknown or missing extensions showed up under "Other":



I'm still not sure of the complete criteria that macOS uses to discern what files fall into what category.  Additionally, it looks like Spotlight won't even try to display a preview of files in the "Other" category even if they are textual.