| 6451 | Optify | 1 |
| 6452 | OptimalGroup | 1 |
| 6453 | Optimax | 1 |
| 6454 | ОПТИМИЗАТОР | 1 |
| 6455 | OPTIMO | 1 |
| 6456 | Optipromo | 1 |
| 6457 | Orange | 1 |
| 6458 | Orange Hat | 1 |
| 6459 | Orange Process | 1 |
| 6460 | ОрбитСофт | 1 |
| 6461 | OrbitSoft | 1 |
| 6462 | Orchid Studio | 1 |
| 6463 | Origami | 1 |
| 6464 | Original Group | 1 |
| 6465 | Orlime Digital | 1 |
| 6466 | ORTA | 1 |
| 6467 | ОСА | 1 |
| 6468 | OscarLab | 1 |
| 6469 | osclass-pro | 1 |
| 6470 | Ошка | 1 |
| 6471 | Осинцев | 1 |
| 6472 | Osk-Market | 1 |
| 6473 | OSMI IT (Ex Осьминожка) | 1 |
| 6474 | Otherwise | 1 |
| 6475 | "Отклик" | 1 |
| 6476 | Открытые ресурсы (г. Киев) | 1 |
| 6477 | ОТМ Россия | 1 |
| 6478 | оура | 1 |
| 6479 | OUT.AGENCY | 1 |
| 6480 | Outreach BRO | 1 |
| 6481 | OVERCLICK | 1 |
| 6482 | OWL agency | 1 |
| 6483 | OWL Agency | 1 |
| 6484 | Oxiv.ru | 1 |
| 6485 | OXY-marketing | 1 |
| 6486 | Oy-li Digital | 1 |
| 6487 | Ozhgibesov.net | 1 |
| 6488 | OZ INTERACTIVE | 1 |
| 6489 | PageFactory | 1 |
| 6490 | PageLab | 1 |
| 6491 | Palex Web | 1 |
| 6492 | Pallada Pro | 1 |
| 6493 | PANAU | 1 |
| 6494 | Panda Ads | 1 |
| 6495 | PANDA Digital Group | 1 |
| 6496 | Panda Moscow | 1 |
| 6497 | Panda-Seo | 1 |
| 6498 | Panda Style | 1 |
| 6499 | Пандаворкс | 1 |
| 6500 | Pandora Research | 1 |
