Almost all existing OneNote versions require your notebooks to be stored in a Microsoft cloud service, namely OneDrive or OneDrive for Business. Is there a way to bypass that restriction?
If you do not want to (or are not allowed to) store your OneNote notebooks in a public cloud service, I have a lot of bad and only one good news for you. Let me start with the good one: The OneNote version for Windows that is installed with MS Office (2010, 2013, 2016) lets you freely choose the storage location for your notebook files. So you can keep them on a local drive or a network share inside your organization. An alternative would be an on-premise Sharepoint server, which also works rather well at least with OneNote 2016 for Windows and OneNote Online (in the browser). You can even share those notes with other users or devices (as long as they run the Office version of OneNote for Windows) if you set the proper access rights to the SharePoint library or network share.
Now for the bad news. All other OneNote versions, so OneNote for MacOS, iOS, Android, Windows 8/10 mobile, OneNote Online and the Windows 10 app, require your notebooks to be stored on a cloud service by Microsoft. This can be OneDrive (personal) or OneDrive for business (aka Sharepoint Online, part of some Office 365 subscriptions). You can’t even switch to another cloud service like Dropbox or Google Drive, because those don’t support the protocol needed for a correct note synchronization. More detail about this in this article.
So if you are reading this article hoping for a workaround to use any OneNote app without a Microsoft account, an Office 365 subscription and OneDrive, I am sorry to disappoint you. I wrote this mainly to confirm that there is absolutely no way around these prerequisites.
But what about all OneNote apps being able to work offline?
Apparently, you can edit existing notes or add new ones without an active internet connection on any OneNote app and system. So the notes must be stored on the device, right? Yes, they are. But this offline cache is in a special format (binary files, all very split up) and only used by OneNote to temporary work with a copy to synchronize the content with the actual storage location later, when an internet connection is re-established.
Now it could come to your mind to create a notebook on OneDrive (notebooks can’t be created on your device while it is offline), open it on your Mac or iPad, delete the original file from OneDrive using your browser and from then on only work in that cached local copy. Yes, you could do that and the only obvious drawback would be a constant sync error that you could just ignore. But I strongly advise against that method, because that cached copy is rather fragile. Closing a notebook, resetting your OneNote settings or probably an upcoming app update will erase the local cache and delete all your notes without any recovery options.
So the point is: If you want to use OneNote on Mac, iOS, Android, Windows 10 mobile or the Windows 10 UWP app, you have to store your notebooks on OneDrive or OneDrive for Business. Again, sorry if this is bad news.
Why is Microsoft doing this?
Well, if you ask any Microsoft representative, the usual answer is: “Because the cloud is better, safer and more reliable than any local drive”. I consider that half of the truth at best and mostly marketing twaddle. But I am sure that there are two real reasons. One is merely political. In 2014 Microsoft CEO Satya Nadella declared a change of course and that the future of Microsoft (products) would now lie in “Cloud first, mobile first”. Forcing OneNote users to the Microsoft cloud services is just a consequence of this new directive.
The second reason is of a technical nature. Because of the way how OneNote synchronizes data (only updating changes to single objects inside a file instead of the whole file), a special protocol is needed. This is called COBALT or MS-FSHTTP by Microsoft and is only supported by Sharepoint and OneDrive. Even locally stored notebooks (with OneNote for Windows/desktop only) are handled in a way that is close to that COBALT protocol. I bet this could not be easily reproduced on the MacOS or iOS file systems. And given the first reason, it is very unlikely that Microsoft would put any effort in it.
Will Microsoft change their mind?
Who can say that? And if they will, will they change it in the “right” direction or maybe also remove the option to store notebooks locally from OneNote for Windows. Or completely remove the desktop version of OneNote (with Office 2019?), only leaving the Windows 10 app. But you can still try to add your vote for local storage to come on the Uservoice foums for OneNote for Mac, OneNote for iOS, Android or the Windows 10 app.