NTest

NTest¹ is a free Othello/Reversi program created by Chris Welty (not to be confused with the other computer scientist named Chris Welty who worked on the IBM Watson project).

NTest is a strong Othello program with a high-quality evaluation function and fast search algorithms. It has many features, with the most important one being the display of the search evaluation for all possible moves.² NTest is among the strongest programs in the world. It is able to do bitboard-based move generation and parallel searches on multiple CPU cores.

Other programs' opening books—such as Edax's book—can be used in NBoard, the GUI created by Chris Welty for NTest.³