ChessSuggest.com is powered by an open source chess engine called Stockfish.
What originally began with code from a project called Glaurung, Stockfish was created in November of 2008 by a developer named Marco Costalba. He was soon joined by two other chess enthusiasts and programmers, Tord Romstad and Joona Kiiski, as Stockfish slowly became the de facto standard in open source chess engines.
Stockfish is available in many forms right now. You can download source code, binaries and even Mac and iOS applications at stockfishchess.org/download.
If you are interested in getting involved in the Stockfish project you can learn about ways you can contribute at stockfishchess.org/get-involved.