What's common between Kovid Goyal & Antony Lewis?

Kovid Goyal

Antony Lewis

They are both PhDs in Physics and creators of free software applications that have been downloaded by millions.

Kovid Goyal is the creator of calibre,  a comprehensive suite of utilities for managing/converting/viewing e-books and news in digital formats while Antony Lewis is the creator of WordWeb,  English dictionary, thesaurus and word finder program for Microsoft Windows, iOS, Android and Mac OS X.

The free version of WordWeb has been downloaded over 5 million times while calibre has been downloaded by 18 million people.

calibre is released under GNU GPLv3 as the author did not want people creating proprietary software based on my work

WordWeb is free subject to very unique licensing terms:

You may use the program free of charge indefinitely only if

• You take at most 4 flights (2 return flights) in any 12 month period

• AND you do not own or regularly drive an SUV (sports utility vehicle).