Serena Dimensions RM - Serena Dimensions RM is a web application to improve the definition and management of requirements across the product lifecycle.

rmtoo - rmtoo is a free and open source requirements management tool.

ReqView - Simple and powerful requirements management tool enabling easy requirements gathering, traceability tracking and offline collaboration.

Rational RequisitePro - The list below identifies the supported releases of IBM Rational RequisitePro from which you can select system requirements in different levels and organization of detail.

Visure - Visure offers  a flexible , modern and complete requirements ALM Platform (Application Lifecycle Management).

Doorstop - Requirements management using version control.