# Meta open-sources Rebalancer assignment solver

> Meta released the C++/Python library Rebalancer, used internally for shard and traffic placement, under an Apache 2.0 licence.

Oossa · 2026-10-07 · https://oossa.com/en/meta-open-sources-rebalancer-assignment-solver

Meta has made its Rebalancer library publicly available. The tool, written in C++ with a Python wrapper, has been used by the company for more than nine years to assign shards, servers and traffic. Meta says it processes about 40 million placement problems each day, using local‑search heuristics or mixed‑integer programming solvers such as Gurobi, FICO Xpress and HiGHS. The library can be installed with pip and is released under the permissive Apache 2.0 licence.

## The facts

- Meta open‑sourced Rebalancer on 2026‑10‑07.
- The system handles roughly 40 million assignment problems per day.

## Why it matters

Developers can now use Meta’s high‑volume placement engine for their own resource‑allocation tasks without building it from scratch.

## Sources & references

1. [Meta AI Open-Sources Rebalancer: A C++ Assignment Solver That Runs About 40 Million Placement Problems a Day](https://www.marktechpost.com/2026/10/06/meta-ai-open-sources-rebalancer-a-c-assignment-solver-that-runs-about-40-million-placement-problems-a-day/) – MarkTechPost, 2026-10-07

Last updated: 2026-10-07