| triple-i new media system design GmbH | Hesse |
| TripleCheck | Hesse |
| TripleCheck GmbH | |
| Trips GmbH | North Rhine-Westphalia |
| Tripuls Media Innovations GmbH | North Rhine-Westphalia |
| TriRhena Consulting e.V. | |
| Trisinus GmbH & Co. KG | North Rhine-Westphalia |
| Trismile GmbH | Berlin |
| TRIsoft Fischer & Stephan oHG | Lower Saxony |
| Tristan Network Construct GmbH | North Rhine-Westphalia |
| TRITEC Electronic AG | Rhineland-Palatinate |
| Tritec GmbH | Lower Saxony |
| Tritec Systeme GmbH | Baden-Württemberg |
| Tritech Computer GmbH | Lower Saxony |
| Tritum GmbH | Thuringia |
| Trivago N.V. | |
| TRL-Funksysteme GmbH | Hesse |
| Troi GmbH | Bavaria |
| Troisdorfer Linux User Group | North Rhine-Westphalia |
| TronicPool GmbH | Baden-Württemberg |
| Trop-Electronic GmbH | North Rhine-Westphalia |
| Tropper Data Service AG | North Rhine-Westphalia |
| Troy GmbH | |
| True Digital Partners | North Rhine-Westphalia |
| True Growth Verwaltungs GmbH | |
| True Node GmbH | |
| truffls | |
| TRUK-Soft Köln Gmbh & Co. KG | North Rhine-Westphalia |
| TRUMPF Hüttinger GmbH & Co. KG | Baden-Württemberg |
| Trustami GmbH | |
| Trusted Network GmbH | Bavaria |
| Trusted Shops GmbH | North Rhine-Westphalia |
| Trustner GmbH | Baden-Württemberg |
| TrustYou GmbH | |
| TruVenturo GmbH | |
| TrySim | Lower Saxony |
| TS Ventures GmbH | North Rhine-Westphalia |
| TSA Törner Software & Systems GmbH | Hesse |
| TSCNET Services GmbH | |
| tsd Technik Sprachendienst GmbH | North Rhine-Westphalia |
| tse Gesellschaft für Technologieberatung und Systementwicklung mbH | Hamburg |
| TSE Systems GmbH | Berlin |
| tsenso GmbH | |
| TSN Systems GmbH | |
| TSP systems GmbH | Rhineland-Palatinate |
| TSS-Software Steffen Schmidt | Baden-Württemberg |
| TSUBIS GmbH | Bavaria |
| TT-Software/Databases | Baden-Württemberg |
| TTI Ing. Büro B. Peter Schulz-Heise | Hesse |
| ttt-it AG | Rhineland-Palatinate |