| ONSCREEN, Inc. | 🍎 | 1 | 4.9★ | Utilities |
| ONSIGHT SOFTWARE (PTY) LTD | 🍎 | 1 | 4.8★ | Business |
| ONSOFFOUR OU | 🍎 | 1 | 4.5★ | Productivity |
| ONTEL PRODUCTS CORPORATION | 🍎 | 1 | 4.6★ | Games |
| ONUR SAHIN | 🍎 | 1 | 5.0★ | Music |
| ONVIT CO.,LTD | 🍎 | 1 | 3.9★ | Finance |
| ONVY HealthTech Group GmbH | 🍎 | 1 | 4.1★ | Health & Fitness |
| ONYAKA GIDA INSAAT SANAYI VE TICARET ANONIM SIRKETI | 🍎 | 1 | 4.5★ | Shopping |
| OODLZ - Cashback With Interest | 🍎 | 1 | — | Shopping |
| OOFT Limited | 🍎 | 1 | 5.0★ | Food & Drink |
| OOKBEE U COMPANY LIMITED | 🍎 | 1 | 4.5★ | Entertainment |
| OOMPH Fitness Inc | 🍎 | 1 | 4.7★ | Health & Fitness |
| OOO "FIT" | 🍎 | 1 | 5.0★ | Finance |
| OOO JilfondService | 🍎 | 1 | 4.8★ | Finance |
| OOO MakaMaka | 🍎 | 1 | 5.0★ | Social Networking |
| OOO Rhyboo | 🍎 | 1 | 4.4★ | Games |
| OOO Zaycev.Net | 🍎 | 1 | 3.0★ | Music |
| OOVA inc. | 🍎 | 1 | 4.4★ | Health & Fitness |
| OP Execution LTD | 🍎 | 1 | 3.0★ | Utilities |
| OP Osuuskunta | 🍎 | 1 | — | Finance |
| OP3N, LLC | 🍎 | 1 | 4.9★ | Music |
| OPA MARKETING TECH PRIVATE LIMITED | 🍎 | 1 | 1.0★ | Lifestyle |
| OPEN Healthcare | 🍎 | 1 | 5.0★ | Lifestyle |
| OPENGATE TECHNOLOGY INVESTMENT GROUP PTY LTD | 🍎 | 1 | 5.0★ | Developer Tools |
| OPENGIS.ch | 🍎 | 1 | 4.3★ | Productivity |
| OPENKEY, INC. | 🍎 | 1 | 4.7★ | Travel |
| OPENPLANIT LLC | 🍎 | 1 | 4.8★ | Travel |
| OPENREC, Inc. | 🍎 | 1 | 4.1★ | Entertainment |
| OPENSTREET CO.,LTD. | 🍎 | 1 | 2.9★ | Travel |
| OPENSURVEY INC. | 🍎 | 1 | 4.7★ | Lifestyle |
| OPERATION MANAGEMENT ENTERPRISE, INC. | 🍎 | 1 | 3.4★ | Business |
| OPERION LIMITED | 🍎 | 1 | — | Utilities |
| OPIO LLC | 🍎 | 1 | 4.2★ | Travel |
| OPMS Co., LTD. | 🍎 | 1 | 3.0★ | Book |
| OPTIFUN | 🍎 | 1 | 4.4★ | Entertainment |
| OPTIMUM ENDUSTRIYEL TEMIZLIK VE KIMYASAL URUNLER SANAYI TICARET ANONIM SIRKETI | 🍎 | 1 | 4.5★ | Photo & Video |
| OPTIMUM FOR SOFTWARE SOLUTIONS | 🍎 | 1 | — | Business |
| OPTIO CZ s.r.o. | 🍎 | 1 | 5.0★ | News |
| OPTIONS COUNSELING SERVICES OF OREGON, INC. | 🍎 | 1 | — | Medical |
| OPTIVAL HEALTH SOLUTIONS PRIVATE LIMITED | 🍎 | 1 | 4.7★ | Medical |
| OPTO | 🍎 | 1 | 4.0★ | Finance |
| OPTOELECTRONICS FUTURE LTD | 🍎 | 1 | — | Games |
| OPTiM Corporation | 🍎 | 1 | 5.0★ | Business |
| OPUS VIRTUAL OFFICES, LLC | 🍎 | 1 | 2.9★ | Lifestyle |
| ORA Developers | 🍎 | 1 | — | Lifestyle |
| ORA Technologies SAS | 🍎 | 1 | — | Food & Drink |
| ORAIMO MOBILE LIMITED | 🍎 | 1 | 4.5★ | Shopping |
| ORANGE CAT TECHNOLOGIES LLC | 🍎 | 1 | 4.0★ | Shopping |
| ORAVEL STAYS LIMITED | 🍎 | 1 | 4.6★ | Travel |
| ORBIS, Inc | 🍎 | 1 | — | Education |