Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
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.
Service - Customer service issues solved for you, on demand, for free.
Planyway - Visual project management for Jira and Trello: manage resources, build project roadmaps, use time tracking.
Customer Service Academy by Freshdesk - Become a customer service expert with video lessons 🎓
Corrello - Dashboards for agile teams using Trello