You can open this file using any application that can open a SQLite database. This is an open format, meaning your data should be readable for decades to come.

AFAIK, the contact database on iOS is an SQLite database file. I checked the backup for an iPhone running iOS 4 (the oldest backup I have), and the file is called 'AddressBook.sqlitedb', but ...

You convert old Sticky Notes StickyNotes.snt data file to the new Sticky Notes plum.sqlite data file so that you can use the Windows 7 legacy Sticky Notes on Windows 11/10.