This repository implements the Facebook Open Switching System (FBOSS), a production network switch operating system used in Meta's data centers. The codebase controls and manages network switches by running a software agent on each switch that programs hardware forwarding ASICs, implements control-plane protocols (ARP, NDP, LLDP, LACP), and provides Thrift-based APIs for external routing controllers. It encompasses a distributed architecture with multiple daemons: the core agent (SwSwitch, HwSwitch), a state database (FSDB) that publishes/subscribes to operational state and stats, a CLI (fboss2) with a trait-driven command framework, platform services (fan, sensor, LED, QSFP transceiver management, firmware updates), and extensive hardware abstraction layers for Broadcom BCM and SAI-based ASICs. A significant portion of the codebase supports multiple switch platforms (Wedge, Minipack, Meru, Janga, etc.) with platform-specific mappings, LED managers, and test harnesses. The open-source release includes OSS stubs for internal Meta features, SDK version conditionals, and a build system based on getdeps.py/FB code builder.