Exeter serves a broad range of organizations, including the following recent clients:
- Brookhaven National Laboratory
- Defense Logistics Agency Energy
- Fermi National Accelerator Laboratory
- General Services Administration
- Lawrence Berkeley National Laboratory
- Lawrence Livermore National Laboratory
- National Association of Regulatory Utility Commissioners
- National Nuclear Security Administration
- National Renewable Energy Laboratory
- SLAC National Accelerator Laboratory
- Strategic Petroleum Reserve
- U.S. Air Force – Air Force Civil Engineer Center
- U.S. Army – Commercial Utilities Program, U.S. Army Corps of Engineers
- U.S. Department of Defense
- U.S. Department of Energy
- Western Area Power Administration – Desert Southwest Region