Up until now; checking in or discarding multiple check out documents in a SharePoint document library at one time, has been a frustrating and time consuming chore for all users.
SharePoint Batch Check In solves that problem, improving user productivity and engagement with SharePoint.
Now you can:
How it works:
Imagine you have a document library where 3 documents are showing they are still checked out.

On the Drop down menu click "Check In Multiple Documents"

You can also "Create major and minor (draft)" versions on the version setting page or select which version to check in.

Now select the documents to be Checked In

You can also include Sub-Folders

You can select all unselect all documents

And enter any required comments

Now click "Check In" to check in all the selected documents