LEMON is an open source graph library written in the C++ language providing implementations of common data structures and algorithms with focus on combinatorial optimization tasks connected mainly with graphs and networks.

LEMON is an abbreviation of Library for Efficient Modeling and Optimization in Networks.

The tools of the library are designed to be versatile, convenient and highly efficient.

LEMON provides LEMON also contains some metaheuristic optimization tools and provides a general high-level interface for several LP and MIP solvers, such as GLPK, ILOG CPLEX, CLP, CBC, SoPlex.

For example, it provides simple tools for measuring the performance of algorithms, which can be used to compare different implementations of the same problem.