MicroPather is a path finder and A* solver (astar or a-star) written in platform independent C++ that can be easily integrated into existing code. MicroPather focuses on being a path finding engine for video games but is a generic A* solver. MicroPather is open source, with a license suitable for open source or commercial use.
An overview of using MicroPather is in the readme or on the Grinning Lizard website: http://grinninglizard.com/micropather/
1.5.1-p1