Opening Microsoft Office OneNote files without OneNote being installed can be a bit of a pain but it is possible and therer are numerous options to do so. Below I will provide a couple different ways to go about reading the OneNote notebook or file. The first of which is if someone has sent you a .one (OneNote) file and you want to open it without having to ask them to provide a different format. The second method will be providing them numerous different formats that they could provide you the OneNote file in including Microsoft Word (.doc and .docx) and HTML.
The first method I will explain is opening the file without having to ask the person who sent you the file to do anything. Regardless of what method you want to use to view the files you will be required to download and install the trial of Microsoft Office OneNote that lasts for 60 days. After 60 days you should still be able to view files but you will not be able to edit them.