Rebalancer is a C++ library with Python bindings for defining and solving assignment problems—placing objects into containers under constraints and optimization goals.

It provides a local-search solver for large-scale problems and a mixed-integer programming solver (HiGHS, Gurobi, FICO Xpress) for guaranteed-optimal results. Meta uses it for hardware and server allocation, ML training/inference placement, traffic routing, and load-balancing migrations.