firemodels/fds

FDS (Fire Dynamics Simulator) is the global de facto standard for fire protection engineering. Developed primarily by NIST, its defensibility is not just in its codebase, but in its massive verification and validation (V&V) corpus—thousands of pages of documentation comparing simulation results to real-world physical experiments. A competitor (even a frontier lab) cannot simply 'code' a replacement; they would need to replicate decades of empirical physical testing to achieve the same level of regulatory and industry trust. The high fork-to-star ratio (nearly 1:1) indicates a deeply technical user base that treats the repo as a critical infrastructure tool rather than a library to be 'liked.' While frontier labs are exploring AI-accelerated CFD (Computational Fluid Dynamics), the specific domain of fire safety is highly regulated and risk-averse, making displacement by 'black box' neural solvers unlikely in the next decade. Commercial competitors like PyroSim already exist, but they build on top of FDS rather than trying to replace its core solver.