Sumatra PDF is a completely free and open source PDF document reader which allows you to view and annotate any document stored on your hard disk. The program can be used with PDF files, but it also allows you to open eBooks in epub and mobi format, comics in cbz and cbr format, and documents in DjVu, XPS and CHM format.
Lightweight, fast and customizable
What makes Sumatra PDF stand out from other similar programs is how lightweight it is. Apps like Adobe Acrobat Reader, to give a well-known example, take up to 80 times more space on the hard disk. Yes, you read that right. Sumatra PDF is 80 times smaller in size than other apps with very similar features. The benefits of this don't stop at saving some memory space. The program is also much faster and consumes far fewer resources as a result.
Learn how to use keyboard shortcuts
Sumatra PDF also offers a host of keyboard shortcuts which, of course, can be customized to suit you. You can take a look at the full list of keyboard shortcuts on the official website, which allow you to quickly move to the first or last page (Home, End), switch between a single and double page view (ctrl+6, ctrl+7), rotate a page clockwise or anti-clockwise (ctrl+shift+-, ctrl+shift++), and so on. Learning to master some of these shortcuts is sure to save you time in the long run.
Convenient tabs for document management
Sumatra PDF allows you to have as many documents open simultaneously as you like. You can have them all open in different tabs and freely switch between them. From the main tab you can see all the documents you have recently opened or, if you prefer, those you have marked as favorites. So, if you are working or studying and want to always have a PDF at hand, you can do so. The program's lightness means you can easily have half a dozen documents open without seeing any impact on your PC's performance.
Annotations and bookmarks
As you might expect from a program of this type, Sumatra PDF allows you to add annotations to any PDF document. Simply select any text or image and add an annotation right next to it. The app also has a very good system of bookmarks. You can quickly access any section of a book or PDF document from a drop-down column on the left side of the screen. It's important to note that this option is only available for books with bookmarks, which includes almost all modern ones. Many older or unofficial PDFs, for example, do not contain bookmarks.
An outstanding PDF document reader
Sumatra PDF is by far one of the best PDF readers on the market today. The program is completely free, lightweight, powerful, versatile and customizable. It is undoubtedly a very useful tool for anyone who works with PDF documents on a regular basis. Unlike other similar programs, moreover, it will never bother you with regular requests to update it, or anything like that.
3 reviews 
Comments
The best reader I've used! - Excellent tool! Lightweight, fast, useful, straight to the point, without that endless array of useless add-ons that cause performance loss! Rating: 10!
It is quick and simple, great for people who don't have much knowledge, in addition to being practical. Generally, users are hurried and don't have much time to read manuals.