Sumatra PDF – For windows
What is Sumatra PDF?
Sumatra PDF is a slim, free, open-source PDF viewer for Windows.
Why another PDF reader?
Sumatra has a minimalistic design. Simplicity has a higher priority than a lot of features.
It's small and starts up very fast.
It's designed for portable use: it's just one file with no external dependencies so you can easily run it from external USB drive.