Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Linear - Streamlined issue tracking for software teams
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
Distiller - Distiller's hosted continuous integration platform takes the pain out of mobile development through automated build, test, and deployment of your iOS apps.
Slack - A messaging app for teams who see through the Earth!
BugHerd - BugHerd: The Website Feedback Tool for Agencies