| TissUse GmbH | |
| Titan Networks Internet & Telecommunications Service Providing GmbH | |
| Tivola Publishing GmbH | Hamburg |
| Tk telefoncall GmbH | Baden-Württemberg |
| TK-Schulsoftware GmbH & Co. KG | |
| TK-Soft | Baden-Württemberg |
| TK-Vertrieb | Brandenburg |
| TKM Telekommunikation und Elektronik GmbH | North Rhine-Westphalia |
| TKR GmbH & Co. KG | Schleswig-Holstein |
| TL Electronic GmbH | Bavaria |
| TLGG Agency GmbH | |
| TM-SOFT | Baden-Württemberg |
| tm-webentwicklung GmbH | North Rhine-Westphalia |
| TME Pharma AG | |
| TMI-Webdesign, Roeder & Dahl GbR | Brandenburg |
| TMKIS Internet Services | Hesse |
| TMT GmbH & Co. KG | Bavaria |
| TNG Technology Consulting GmbH | Bavaria |
| TNM Software GmbH | Saarland |
| to-teach.ai | |
| TOA Electronics Europe GmbH | Hamburg |
| TOA Festival | |
| TOASTER Internet UG(haftungsbeschränkt) & Co. KG | North Rhine-Westphalia |
| Tobax Software GmbH | North Rhine-Westphalia |
| Tobias Hüllmandel Softwareentwicklung | Baden-Württemberg |
| Tobias Krähling | North Rhine-Westphalia |
| Tobias Kühn | Bavaria |
| Tobias Schnorr | Hesse |
| Tobias Ulm | Bavaria |
| Tobit.Software | North Rhine-Westphalia |
| TodaySystems GmbH | |
| todo GmbH | Berlin |
| tog.is information design | Bavaria |
| Tokenize.it | |
| tokenstreet GmbH | |
| Tolerant Software | |
| TolerogenixX GmbH | |
| Tolingo GmbH | |
| Tomcom GmbH | Bavaria |
| Tomorrow GmbH | |
| Tomorrow University of Applied Sciences | Berlin |
| TOMTEC Imaging Systems GmbH | Bavaria |
| TonerPartner GmbH | North Rhine-Westphalia |
| Tonfunk Elektronik Systeme GmbH | Saxony-Anhalt |
| toolbox Software GmbH | North Rhine-Westphalia |
| Tools of Innovators GmbH | |
| ToolStage Software Engineering | Hesse |
| Top 21 Systemhaus GmbH | |
| top itservices AG | Bavaria |
| TOP TEN Computervertrieb GmbH | Bavaria |