| OpenKey | Texas |
| OpenLaw | |
| Openlayer | California |
| OpenLight Photonics, Inc. | |
| OpenLink Software, Inc. | Massachusetts |
| OpenLM, Inc. | Delaware |
| OpenLoop | Iowa |
| OpenMachine | |
| OpenMake Software | Illinois |
| OpenMarket | Washington |
| OpenMarkets, Inc. | |
| OpenMeter | |
| OpenMethods | California |
| OpenMind | |
| OpenMined | |
| OpenName, LLC | California |
| OpenOakland | |
| OpenObserve | California |
| OpenOffice | California |
| OpenOrgs.info | |
| Openpath, Inc. | California |
| OpenPhone Technologies, Inc. | California |
| OpenPotion, Inc. | California |
| OpenPro, Inc. | California |
| OpenQuant | |
| OpenRDA | Georgia |
| OpenResty, Inc. | |
| OpenRounds, Inc. | |
| OpenRouter, Inc. | |
| OpenSales, LLC | |
| OpenSCAP | |
| OpenScholar, LLC | |
| OpenSea | |
| OpenSearchServer, Inc. | |
| OpenShift | North Carolina |
| OpenShot Studios, LLC | Texas |
| OpenSource Technologies | Pennsylvania |
| OpenSource, Inc. | California |
| Opensource.com | North Carolina |
| OpenSourceCMS.com | Illinois |
| OpenSponsorship Corporation | |
| OpenStax | Texas |
| OpenStore | Florida |
| OpenSystems Media | Arizona |
| OpenTech Alliance, Inc. | Arizona |
| OpenThought | Pennsylvania |
| OpenUnit, Inc. | |
| OpenVC | California |
| OpenView Venture Partners | Massachusetts |
| Openvine Solutions, Inc. | |