IsItPrime
A small, basic, yet powerful and competent primality tester.
IsItPrime is a powerful, cross-platform, multi-threaded standalone application capable of testing massive numbers in several ways through a highly interactive and easily-understood user interface.
As of version 2.0.0, IsItPrime and other NCPrime applications no longer require the Visual C++ 2010 Redistributable for Windows. All NCPrime applications released after 1 November 2012 use the Qt framework and thus require Qt libraries (included) for cross-platform compatibility.
IsItPrime is in active development.