rmtoo - rmtoo is a free and open source requirements management tool.
Aspen Plus - Maximize profits using a plant-wide simulation solution that combines unparalleled accuracy and engineering collaboration with time-saving workflows.
Doorstop - Requirements management using version control.
Valispace - Valispace is a modern browser based tool for complex hardware development that connects data for engineers, efficiently manages requirements and much more.
Reqflow - Reqflow is a free and open-source tool for traceability of requirements across documents, designed to analyse documents with speed and efficiency.
EPLAN Electric P8 - CAE software solution for project planning, documentation and administration of electrotechnical automation projects.