What is Bugzilla?
Bugzilla is a robust, featureful and mature defect-tracking system, or bug-tracking system. Defect-tracking systems allow teams of developers to keep track of outstanding bugs, problems, issues, enhancement and other change requests in their products effectively. Simple defect-tracking capabilities are often built into integrated source code management environments such as Github or other web-based or locally-installed equivalents. We find organizations turning to Bugzilla when they outgrow the capabilities of those systems - for example, because they want workflow management, or bug visibility control (security), or custom fields.
Bugzilla is both free as in freedom and free as in price. Most commercial defect-tracking software vendors charge enormous licensing fees. Despite being free, Bugzilla has many features which are lacking in both its expensive and its free counterparts. Consequently, Bugzilla is used by hundreds or thousands of organizations across the globe.
Bugzilla is a web-based system but needs to be installed on your server for you to use it. However, installation is not complex.