You can switch from the single page mode, to the continuous, two-page or two-page continuous modes, while also adjusting the zoom level to your preferences.

Should you come across an encrypted document, the app requires you to enter the correct password, then displays the file's contents.

You can easily open any PDF you might need, by either browsing to its location or by dropping it onto the main window of PDF Extra. PDF Extra is one of the many options you get, and it also supports some editing operations to make your life easier. Since PDF is a proprietary format, you typically need a dedicated software utility to view this type of documents outside a compatible browser.