Many might not consider WhatsApp a full-fledged social media platform, but things have changed. Facebook-owned WhatsApp has made its mark in the industry with new features flooding in the App, every other month. It has recently launched video status update with customization options. It has borrowed a feature from Telegram and introduced one way broadcasting on the group chat. WhatsApp also introduced a web client to use the service through a desktop browser, which we found satisfyingly good.
PicPlz used to be my personal favorite, until pressure from Instagram on Android forced them to shut down. In their place though, a new challenger has risen—one with an old name. Flickr's new Android app brings most—if not all—of the same features that Instagram offers and combines them with Flickr's own photo-centric social network where your photos belong to you and no one else. Flickr's new Android app lets you take photos straight from your camera and apply filters to them if you choose, then share them with friends on Flickr, Facebook, Twitter, or anywhere else you choose.
A simple chat (slack style) it's enough. Just having the possibility to send messages either single user or team (#channel). But please don't forgive to give an useful appeal to mobile app (worst error of competitors is, have a good app but totally no mobile friendly!) i would expect to have a similar whatsapp or slack app for messaging within the slack mobile app!