Sumatra PDF is a free, open-source reader for Windows that opens instantly and stays out of your way. Beyond PDF it also reads ePub, MOBI, CHM, XPS, DjVu and comic book archives.

Key features

• Extremely fast startup and rendering

• Reads PDF, ePub, MOBI, CHM, XPS, DjVu, CBZ/CBR

• Portable single-file version available

• Keyboard-driven, minimal interface

• Free and open source

Is Sumatra PDF free?

Yes. Sumatra PDF is free and open source (GPL) for Windows.