What is the newest MIP or CP solver (which is model based exact solver)?

I want to follow and wonder developments on solvers. But finding new developed solvers (experimental, academic, commercial etc.) with search is not enough, and sometimes can be missed. Answers to this question can be guiding.


2 Answers 2


Below are some popular solvers for MIP & CP (Not an exhaustive list though)

  1. MIP Solvers: Gurobi, CPLEX, XPRESS(FICO), CBC, SCIP, etc..
  2. CP Solvers: MiniZinc, OR-Tools, CP Optimizer(CPLEX), etc..

One of the newest solver that I can across recently for LP/MIP/QP was HIGHS.

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    $\begingroup$ Note that MiniZinc is not a CP solver -- it is a high level language which can generate input for other other CP (and MIP and SAT) solvers. $\endgroup$ Commented Feb 1, 2022 at 9:53

OptaPy might be the newest solver at the time of writing.

OptaPy is an open source Python solver that uses parts of OptaPlanner inside (but it's considered a different solver). It was announced on 5 October 2021.

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    $\begingroup$ It may not even be a solver: it does not know when a problem is solved. $\endgroup$ Commented Jan 31, 2022 at 8:08
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    $\begingroup$ I think the name "solver" implies that it knows when an optimization problem a solved. So no, a heuristic in my view is not a solver. It does not really "solve" a problem. Unless you restate the problem as "give me a good solution for ..." (where good really means "not bad"). There is just no concept of optimality in (most) heuristics. $\endgroup$ Commented Jan 31, 2022 at 8:13
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    $\begingroup$ OR-Tools and LocalSolver can find guaranteed optimal solutions. Yes, they are proper solvers. They solve optimization problems. They know when they are done and the problem is solved. $\endgroup$ Commented Jan 31, 2022 at 9:56
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    $\begingroup$ I agree with @GeoffreyDeSmet here, I don't consider the notion of solver to be related to optimality, but rather to finding solutions or bounds. Would IPOPT stop being a solver when executed on a non-convex problem? In addition, MILP and CP solvers are often used just as heuristics $\endgroup$
    – fontanf
    Commented Jan 31, 2022 at 10:06
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    $\begingroup$ You should add a disclaimer acknowledging your bias when advertising your own projects. $\endgroup$ Commented Jan 31, 2022 at 13:44

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