| ISB AG | Baden-Württemberg |
| ISBE GmbH | |
| ISC Group | Baden-Württemberg |
| ISCOM Consulting | Brandenburg |
| ISCOPE GmbH | Lower Saxony |
| ISCP Internet Service e.K. | Schleswig-Holstein |
| iseg Spezialelektronik GmbH | Saxony |
| isel Germany AG | Hesse |
| ISEO GmbH | Schleswig-Holstein |
| ISG Industrielle Steuerungstechnik GmbH | Baden-Württemberg |
| ISG Institut für Sozialforschung und Gesellschaftspolitik GmbH | |
| ISI agentur | Baden-Württemberg |
| isle Steuerungstechnik und Leistungselektronik GmbH | Thuringia |
| isLOGIC AG | Brandenburg |
| ISM International School of Management GmbH | |
| ISN GmbH | Saxony-Anhalt |
| ISO Software Systeme GmbH | Bavaria |
| Isotronic GmbH | Bavaria |
| ISOware GmbH | Bavaria |
| isp-kommunal | Lower Saxony |
| ISP-Tools GmbH | Bavaria |
| ISPHTTP Webhosting Provider | Hesse |
| ISR Information Products AG | Lower Saxony |
| Isra Vision AG | Hesse |
| Isra Vision Parsytec AG | North Rhine-Westphalia |
| ISS GmbH | Bavaria |
| iss innovative software services GmbH | Baden-Württemberg |
| ISS Internet Services | |
| IST-Hochschule für Management GmbH | |
| istari.ai GmbH | |
| istis GmbH | North Rhine-Westphalia |
| isyControl Software | Bavaria |
| iSYS Software GmbH | Bavaria |
| iSYSTEM AG | |
| IT & More GmbH | Bavaria |
| IT + Media Group GmbH | Baden-Württemberg |
| IT AUDIT GmbH | North Rhine-Westphalia |
| IT Bergischesland Wuppertal | North Rhine-Westphalia |
| IT Consulting Kühnl | |
| IT Craft YSA GmbH | Berlin |
| iT Engineering Software Innovations GmbH | Baden-Württemberg |
| IT Factum GmbH | Bavaria |
| IT Gesellschaft für Informationstechnik mbH | Bavaria |
| IT Innovations GmbH | Bavaria |
| IT Logistik | |
| IT Management Consulting Group Gesellschaft mit beschränkter Haftung | Lower Saxony |
| It Marketing Solutions | |
| it Matters Games UG | |
| IT Process Maps GbR | Bavaria |
| IT Schnittstelle | Hesse |