There's also COIN-OR: https://www.coin-or.org/ https://www.coin-or.org/ When i compared them a year or so ago, my conclusion that OR-Tools had more focus on e

There's also COIN-OR: https://www.coin-or.org/ https://www.coin-or.org/ When i compared them a year or so ago, my conclusion that OR-Tools had more focus on engineering, making the whole thing easy to integrate etc, whilst COIN-OR had more sophisticated solvers, and gave you lots and lots of knobs to tweak.