- Oliveira Monitoramento
- OLive Streaming
- Oll Inklusiv
- OlliChat
- Ollo
- Ollo For Dating
- Olly
- Olove
- OLPH Chattanooga
- Oltner Fasnacht
- Olvid
- Olympia College
- Olympus App
- OM Plus
- We Are One Regional Meeting
- OMA Meetings and Events
- OMA OMA
- Omada - Make Sport Social
- Omapost - stuur een kaartje
- Chat Pal-talk with new friends
- Omega Live Video Broadcast
- On Air Messenger - 語音識別發送消息!
- ON Dispatch
- On The Block - Local Services
- On the Spot Hangout App
- ON TIME・ひまトーク・出会いチャットアプリ
- On-Meet
- ON-计划打卡
- OnAire: Pause Your Moments
- Onclass Messenger
- OnDaySix Christian Dating App
- Ondernemend Tilburg
- Onderwijs portalen
- OnDo: мессенджер с экосистемой
- One Another
- One Billiards AR Experience
- One Call Now Mobile
- 一個聊天 - 所有在一個信使
- 一個聊天 - All-in-One Messenger
- One Christian Love
- One Heddon St