Algorithms for mixed integer problems can be used for continuous and all-integer problems, too.

**Mixed Integer Linear Programming (MILP)**

SCIP |
Framework for Constraint Integer Programming, links to CPLEX, SOPLEX, or CLP as LP solver (C) |

lp_solve |
C, procedural interface. Java wrapper |

Pascal-MILP-solver |
Borland-Pascal sources, DOS/OS2 binaries |

BonsaiG |
C, B&B, dynamic LP, partial arc consistency algorithm, binaries( Linux, Solaris) |

PICO (part of ACRO) |
B&C, using CPLEX, GLPK, or SOPLEX; AMPL interface |

GLPK |
GNU LP library, B&B, dual/revised simplex, interior point, C, Win32-version, Matlab interface, Java interface |

CBC |
Simple branch&cut solver, part of COIN-OR (C++) |

COLIOP |
IDE to solve LP and MILP; uses GLPK as solver; uses modeling language CMPL (C++) |

SYMPHONY |
callable library for solving mixed-integer linear programs, uses Clp as default LP solver (C) |

MATLOG |
(MATLAB) The milp.m solver (needs lp.m from Matlab optimization toolbox) |

**Mixed Integer Quadratic Programming (MIQP)**

MIQPBB |
branch&bound code |

YALMIP |
Matlab toolbox for rapid prototyping of optimization problems, supports many solvers; B&B for mixed integer problems |

MIQP |
part of MPT (Matlab) |

**SDP solvers for discrete optimization**

COPL_SDP |
solves various cut problems, uses dual scaling method(C) |

COPL_DSDP |
mixed integer linear semidefinite problems, enhanced COPL_SDP, MPS-like input (C) |

YALMIP |
Matlab toolbox for rapid prototyping of optimization problems, supports 20 solvers; B&B for mixed integer problems |

Max-AO |
solves SDP relaxations of maximum stable set and maximum clique problems, graph input (C) |

SDPLR |
solves SDP relaxations of the maximum cut, minimum bisection, and Lovasz theta problems, graph input (C) |

**Mixed Integer Nonlinear Programming (MINLP)**

BonMin |
hybrid code from COIN-OR, exact for convex problems |

Minotaur, MINLPBB, MIQPBB |
various codes, exact for convex problems |

LaGO |
B&C, Linux binary, binary variables only, GAMS interface |

BARON |
Branch And Reduce Optimization Navigator (avail. from AIMMS, GAMS) |

BNB |
B&B, Matlab, needs optimization toolbox |

FMINCONSET |
B&B, variables may be restricted to discrete sets, Matlab, needs optimization toolbox |

AlphaEcp |
part of GAMS or through NEOS, exact for convex problems |

LogMIP |
Logical Mixed-Integer Programming, general disjunctive programming (needs GAMS) |

MINLP solvers |
Links to more solvers |

**Pure integer programming**

LocalSolver |
G Local search heuristic for nonlinear 0-1 problems, free for academic use (C++, C#, Java, .NET) |

OPBDPbinaries |
0-1 variables, objective and constraints polynomial (C++) A Davis-Putnam Based Enumeration Algorithm for Linear Pseudo-Boolean Optimization |

CSPLIB/CPlan |
C-library for binary constraint satisfaction problems, application to planning problems |

CirCut |
GPL-licensed f90 code to approximately solve certain binary quadratic problems such as Max-Cut, Max-Bisection etc. |

**A list of problem specific solvers**

perm_mateda |
Matlab toolbox for permutation-based combinatorial optimization problems incl TSP and QAP |

Torsche |
Matlab scheduling toolbox |

TSP software |
Commented list of exact and heuristic traveling salesman software |

Concorde |
The ultimate Traveling Salesman code, includes LK, source in (C), Win/Unix executables |

LKH |
An effective implementation of the Lin-Kernighan heuristic, symmetric and unsymmetric cases, C |

TSPTW |
C++ code using ILOG Solver&Scheduler for TSP with time windows |

Blossom IV |
Minimum weighted perfect matching solver (C); needs Concorde |

Assignment Problems |
links in book by Burkard et al |

STONY BROOK |
The Stony Brook Algorithm Repository mainly for combinatorial problems |

LOLOLA |
a package for planar location and layout problems (solves discrete and continuous cases) |

Hungarian method |
basic f77 code to solve the linear assignment problem |

SKAP |
f77 code for the k-cardinality assignment problem |

QAP |
heuristic algorithms for the quadratic assignment problem |

LEMON |
Library of Efficient Models and Optimization in Networks (C++) |

Cliquer |
exact B&B code to solve various clique problems in weighted graphs (C, GPL) |

QUALEX |
fast heuristic max-weight clique/independent set solver |

Knapsack |
problem generators and solvers, bin-packing, container-loading |

TOMS 864 |
Three-dimensional bin-packing algorithms |

TSpack |
C-code for d-dimensional bin packing |

MATLOG |
Facilities Planning and Logistics Matlab Toolbox |

JOBSHOP |
a package to solve jobshop scheduling problems |

SAT Live! |
up-to-date links for the satisfiability problem |

WALKSAT |
Stochastic Local Search for Satisfiability, source, Linux binaries (C) |

BG-DYN-WALKSAT |
Backbone Guided WalkSAT for SAT and Max-SAT with Dynamic Noise Ratio |

GRASP |
the grasp algorithm for QAP, MAX-SAT and other problems |

MAXSAT |
Borchers' exact algorithm and testproblems for (weighted) MAX-SAT |

GEOSTEINER |
package to compute optimal Steiner and minimal spanning trees |

BIOGEME |
package for discrete choice (GEV) models |

**For more information**

ZIB Optimization |
for some discrete optimization problems: software and testcases |

Operations Research and Related Sites |
mainly a list of useful URL's maintained by John Mitchell |