Zammad

Email-based customer support application, help desk and shared mailbox (alternative to Zendesk and Help Scout).

Marketing, sales, and customer service platform designed to help businesses attract more engaged customers.

Manage, organize and archive all your support requests and responses in one place.

Helpdesk software which helps you streamline your company's support, offers an easy setup, clean user interface, and automation tools to resolve customer queries efficiently.

Modern customer support desk. Single binary app.

Bug tracker, fits best for software development.

Real-time error tracking for your applications with all the details in one place. Easy setup with clear instructions included.

Trudesk is an open-source help desk/ticketing solution.

Enterprise-grade issue tracking system.

Client IT documentation, ticketing, invoicing and accounting for MSPs (Managed Service Providers).

General-purpose bugtracker and testing tool originally developed and used by the Mozilla project.