Export contacts from OWA - Exchange 2016

There is no way to export or drag and drop contacts from OWA. You will need to use a 3rd party app to or outlook. you can export the contact to a pst file from the mailbox via using the exchange management shell. let me know if that if a viable option for you run the below cmdlets in the exchange shell:

New-MailboxExportRequest -Mailbox "username" -IncludeFolders “#Contacts#” -excludedumpster -filepath\\server_name\pst\filename.pst

Are there any easy to use 3rd party apps that will do it with minimal input from the user?

https://www.kerneldatarecovery.com/ offers alot of options for moving mail to pst files but it will still need to connect to a source mailbox database in Exchange or O365. A little know how if needed but very intuitive and they offer tech support.

I don’t think that’ll work. I should’ve mentioned that this is for backup purposes and they’ll need to be able to edit and import their edits back in (after the mailbox has been cleared of all contacts).

OWA is a web version to view exchange mails. Not a complete solution, else no one is going to purchase office or outlook from MS, if OWA can do everything. However, i found something, check if this helps:
https://support.outboundengine.com/hc/en-us/articles/203624504-How-to-export-contacts-from-Office-365-Outlook-Web-Access

Are you the Exchange admin?  If you do have access to the Exchange server then you can do this thru the Exchange Powershell.

http://msexchangeteam.in/export-exchange-contacts-to-pst-or-csv/

Use the instruction in the article for 2013 on 2016.

after you export the contacts to a pst file as I described above using the exchange shell, you can then import them back into the mailbox.

Yes, Tim did mentioned that first.

I'm really looking for a solution for the user as they need to decide which ones to keep and then import back in later.

since you are using owa, there is no easy solutions apart from what I mentioned unfortunately.

I don't have to use OWA, just not all users have access to Outlook :)

Thanks

sure thing and good luck.