Commonwealth Fusion Systems
| Company type | Private | 
|---|---|
| Industry | Energy | 
| Founded | 2018 | 
| Headquarters | Devens, Massachusetts, US | 
| Key people | Bob Mumgaard (CEO) | 
| Number of employees | 1,000+ (2025) | 
| Website | cfs | 
Commonwealth Fusion Systems (CFS) is an American fusion power company founded in 2018 in Cambridge, Massachusetts, after a spin-out from the Massachusetts Institute of Technology (MIT). Its stated goal is to build a small fusion power plant based on the ARC tokamak design. It has participated in the United States Department of Energy’s INFUSE public-private knowledge innovation scheme, with several national labs and universities.