The two main ones I see are Micro.blog and Mastodon. Micro.blog is the more popular one right now, it seems, but Mastodon has its fair share of loyal fans. I personally have accounts with both other services, but I don’t really use them reliably. Mastodon because I can’t find anyone on there, and Micro.blog because I don’t like any of the iOS apps available for it.
The incident is the most high-profile misuse of Facebook's systems to become public, but it's far from the only one. Russian propagandists slipped through Facebook's advertising safeguards to try to influence the 2016 presidential election. In 2014, the social network allowed academics to use the News Feed to tinker with users' emotions. The United Nations even said earlier this month that Facebook played a role in exacerbating the genocide of the Rohingya people in Myanmar. Facebook itself has admitted that mindlessly scrolling on its platform isn't good for you.
Snapchat is a brilliant alternative to Instagram. This is a multimedia messaging app for iPhone and Android users. You can share your photos from here easily. In this app, you can set the time of your chat visibility. Aside from that, what separates Snapchat from the rest is that all photos and videos being shared will disappear in a few seconds after being viewed. When it comes to capturing photos, this app has a variety of filters that you can use to make your capturing experience more fun and enjoyable.
500px has long been popular with the photography community with it's clean approach to photo sharing. No hashtags muddle this pond, 500px is all about sharing great work. Curated collections are excellent and regularly updated, whilst the Exif data upload is a nice touch to delve into the technical workings in-camera (Flickr also has this function). There are plenty of similarities with Flickr in terms of it being a platform angled towards promotion of the best creative work rather than popular accounts and sponsored posts.
@Corvin Adkins: I completely agree. My team and I use Podio and the internal chat is useful for general communication. And even though it integrates with Slack, I don't want my team to have to switch between apps to chat. It would be counter productive. We would love to migrate to Clickup but wouldn't be able to until it had the current features that our team is using on Podio at minimum.