| AS Stallion Ltd | Harju County |
| AS Sysdec | Harju County |
| ASA Quality Services OÜ | Harju County |
| ASBIS-Baltik AS | Harju County |
| Asper Biotech | Harju County |
| Astonsoft Co. | Harju County |
| Astonsoft Ltd | Harju County |
| At Fut | Tartu County |
| ATBM | Harju County |
| Audes OÜ | Ida-Viru County |
| Audiocenter | Harju County |
| AutomatWeb | Harju County |
| Avicom EST OÜ | Harju County |
| Axinom Holding OÜ | Tartu County |
| BaIT Partner OÜ | Harju County |
| BaltCap | |
| Baltic Computer Systems AS | Harju County |
| Baltnet Communications OÜ | Harju County |
| Baltronic OÜ | Harju County |
| Baltronic OÜ | |
| Basical Interactive | |
| BeeServer OÜ | Harju County |
| BestIT OÜ | Harju County |
| Biblioserver | |
| BioAtlas | |
| Black Wing Foundation | |
| Bluemark OÜ | Harju County |
| Bluemoon Interactive | Harju County |
| BPW Consulting | Harju County |
| BSD Eesti | Harju County |
| BuildIT | Harju County |
| BusyBits | |
| Cactus Hosting | Harju County |
| CAD-süsteemide OÜ | Harju County |
| CADi Eesti OÜ | Harju County |
| CATz Soft OÜ | Harju County |
| CityITjobs.net | Harju County |
| Codehoop OU | |
| Commuun OÜ | Harju County |
| Compitek Group OÜ | Harju County |
| Computernik OÜ | Harju County |
| Connect IT OÜ | |
| Connected OÜ | Harju County |
| Coomor OÜ | Harju County |
| Copymax OÜ | Harju County |
| Core Hosting OÜ | Harju County |
| CRM Süsteemid OÜ | Harju County |
| CSC Telecom Estonia | Harju County |
| Cybernetica | Harju County |
| Data Service OÜ | Harju County |