- Oliveira Monitoramento
- OLive Streaming
- Oll Inklusiv
- Oll3H: Business Contact Cards
- OlliChat
- Olly
- Olove
- OLPH Chattanooga
- Oltner Fasnacht
- Olvid
- Olympia College
- Olympus App
- OMA OMA
- Omada - Make Sport Social
- Omapost - stuur een kaartje
- Chat Pal-talk with new friends
- Omega Live Video Broadcast
- Omega Psi Phi On The Go
- OmeTV – Video Chat Alternative
- On the Spot Hangout App
- ON TIME・ひまトーク・出会いチャットアプリ
- On-Meet
- OnAire: Pause Your Moments
- Once Fotoğraflar
- Onclass Messenger
- OnDaySix Christian Dating App
- Ondernemend Tilburg
- Onderwijs portalen
- OnDo: мессенджер с экосистемой
- One Another
- One Billiards AR Experience
- Bir Sohbet - Bir Messenger'da
- Bir Sohbet Messenger
- One Christian Love
- One Connect - Copy Trade
- One Diary - 一日记
- One Heddon St