title: Best open source Mixed Integer Optimization Solver
body: <p>I am using CPLEX for solving huge optimization models (more than 100k variables) now I'd like to see if I can find an open source alternative, I solve mixed integer problems (MILP) and CPLEX works great but it is very expensive if we want to scale so I really need to find an alternative or start writing our own ad-hoc optimization library (which will be painful)</p>
  
  <p>Any suggestion/insight would be much appreciated</p>