When comparing Blossom vs UpWave, the Slant community recommends Blossom for most people. In the question“What is the best task management software for small teams?” Blossom is ranked 17th while UpWave is ranked 19th. The most important reason people chose Blossom is:
An update is posted to the Slack channel every time a task is created, completed, moved, or commented upon.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Slack integration
An update is posted to the Slack channel every time a task is created, completed, moved, or commented upon.

Pro Simple & clean interface
Design focuses on clarity.
Pro Intuitive interface
On UpWave you only have three "rows": To Do, In progress and Completed making it very easy to get an overview.
Pro Integrations
Several integrations: Slack, Teams, Zapier, Office etc.
Pro Easy to switch between different boards
Pro Flexible layout to customise for different purposes
Cons
Con No free plan
There is no free plan like for personal use and the minimal cost of $19/month might be prohibitive.
Con Slack integration is really basic
There is no way to interact with tasks in any way - new tasks can't be added, completed tasks can't be removed, tasks can't be assigned, etc. The integration only sends updates to the Slack channel. There is also no way to fine-tune what updates get posted to Slack.
Con Not free
After a 30-day trial the price is $4 per user, per month.
