From: http://www.liquidplanner.com/lp-pricing/

  Flexible best & worst case planning
  Best case/worst case estimates are a project game changer. Only LiquidPlanner uses them to 
  calculates realistic schedules that reflect the way you actually work. When your priorities 
  change, so do your project plans—automatically. Finally, a better alternative to old-school, 
  rigid project management

From: https://www.zoho.com/projects/zohoprojects-pricing.html

  Zoho Projects is an integrated project management solution that simplifies and speeds every 
  project, every time. Whether your team is 3 or 30, you can make sure everyone’s on the same 
  page and working toward the same goal.
  1 project is free

From: https://freedcamp.com/

  free collaboration platform