TestRail is another competitor of Zephyr and allows for easy integration of the Requirements+Defect management tool called “Version One”
https://support.testrail.com/hc/en-us/articles/7691128664980-Integrate-with-VersionOne
Somos (has procured Zephyr Enterprise licenses) uses Version One for Requirements tracking – Jira (already integrated) with your help yesterday. Now need to integrate VersionOne as well. Can you help or point us to an architect who can help us with the integration?