Google OR-Tools is a free and open-source software suite developed by Google for solving linear programming (LP), mixed integer programming (MIP), constraint programming (CP), vehicle routing (VRP), and related optimization problems. OR stands for operations research.
OR-Tools is a set of components written in C++ but provides wrappers for Java, .NET and Python.
It is distributed under the Apache License 2.0.

History
OR-Tools was created by Laurent Perron in 2011.
In 2014, Google's open source linear programming solver, GLOP, was released as part of OR-Tools.
The CP-SAT solver bundled with OR-Tools has been consistently winning gold medals in the MiniZinc Challenge, an international constraint programming competition.

Features
The OR-Tools supports a variety of programming languages, including:

Object-oriented interfaces for C++
A Java wrapper package
A .NET and .NET Framework wrapper package
A Python wrapper package
OR-Tools supports a wide range of problem types, among them:

Assignment problem
Linear programming
Mixed-integer programming
Constraint programming
Vehicle routing problem
Network flow algorithms
It supports the FlatZinc modeling language.

See also
COIN-OR
CPLEX
GLPK
SCIP (optimization software)
FICO Xpress
MOSEK

References

Bibliography

External links
Official website
Source code
Video introduction to OR-Tools