A free version of OneNote for the Windows desktop also is available for download from OneNote.com as of today. Previously, Microsoft made free versions of OneNote available for Windows 8, Windows Phone and the Web. But until today, users of older versions of Windows had to pay for the OneNote app as part of Microsoft's Office suite.
The new free version of OneNote for the Windows desktop doesn't include all the features in the paid version. It doesn't have SharePoint support, version history or Outlook integration. To get those features, users need to upgrade to the paid version. It's also worth noting that the free version is ad-free, not a temporary trial version, and limited to home/school use only.
Microsoft also announced that it has opened up the OneNote service -- available at OneNote.com -- to third-party developers by making available a cloud programming interface to which applications can be connected. New features available via the OneNote service include OneNote Clipper, which allows users to save Web pages to OneNote; a new email@example.com e-mail feature for sending notes to OneNote; and Office Lens, Microsoft's optical-character-recognition technology for capturing documents and whiteboards with Windows Phone and saving them to OneNote.