It seems like every developer has wanted to create a product like Slack: a product that is not revolutionarily new but is a better designed version of existing products (in this case HipChat or Campfire). This mindset prompts an abundance of Twitter, RSS, Podcast, you-name-it clients. Everyone has their own take on how these utilities should function, and they think that their approach and design sensibilities are the best. Their version is good enough to make it and build an entire business upon.

Additionally, Slack has implemented subscription-based pricing dependent on the number of users and features you require. This pricing strategy is one of the best formulas for a sustainable software business.