| Classic Automation, LLC | New York |
| Classic Business Products | Louisiana |
| Classic City Computing, Inc. | Georgia |
| Classic City Technology | Georgia |
| Classic Components Corporation | California |
| Classic Computers, Inc. | Pennsylvania |
| Classic Micro Systems | California |
| Classic Soft Web Technology | |
| Classic Software | Utah |
| Classic Systems | California |
| Classical Software | California |
| Classkick | Illinois |
| ClassLink | New Jersey |
| ClassOne Equipment, Inc. | Georgia |
| ClassWallet | |
| Classy Websites | |
| Clavax | |
| Clavis Capital Partners | Texas |
| Clay | New York |
| Clay Mathematics Institute | Rhode Island |
| Clay Pot Creative | Colorado |
| Clay Software, Inc. | |
| Clayton Controls, Inc. | |
| Claytowne | California |
| Clazar, Inc. | |
| CLC Compliance Technologies, Inc. | Virginia |
| Clean CSS | Ohio |
| Clean Energy Ventures | Massachusetts |
| Clean Outlook | Indiana |
| Clean Web Design | Idaho |
| CleanBrain Software, Inc. | Utah |
| CleanCapital Holdings, LLC | New York |
| CleanEmail | California |
| Cleanlab, Inc. | California |
| CleanRF Systems | Colorado |
| CleanRouter | |
| Cleanscape Software International | New Mexico |
| CleanSlateUV, LLC | |
| CleanStart | California |
| CleanTech Alliance | Washington |
| Cleantech Open | |
| Cleantech Ventures, Inc. | New Jersey |
| Cleantie | |
| CLEAR | |
| Clear Analytics BI | New York |
| Clear Ballot | Massachusetts |
| Clear Blue Engineering | Colorado |
| Clear C2, Inc. | Texas |
| Clear Channel Outdoor | |
| Clear Choice, Inc. | Georgia |