Zendesk - Zendesk is a beautiful, lightweight help-desk solution.

Oak Engage - Oak Engage is a digital workplace for enterprises that need to communicate with their workforce. Connect your teams. Engage your people.

Zendo - Zendo allows you to sell productized, subscription and custom services. Collaborate and collect payments. Create quotes and invoices. Eliminate multiple tools and enjoy the simplicity.

Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community

Nextcloud Hub - On-premises, enterprise collaboration solution for documents, emails, calendars and more.

SendBoard - Send & Receive emails in Trello, where you can collaborate and get more done. For email help desks, CRM, workflow and automation. Add the Power-Up in Trello.