http://www.scenarioplus.org.uk/vendors.htm by Ian Alexander

Requirements Tools and vendors
Translate your customer’s confused, vague and ambiguous thoughts into truly accurate requirements for more effective solution development and delivery.

Historically there are four types of requirement artifacts that we deal with, functional specification:
-1 the text requirements
-2 the use case, and business/domain glossary
-3 the process-flow diagram
-4 the screen-shots with GUI elements and mockup content

Simulation is actually new type of requirement, the 5th type of specification artifact, which has entered recently among the product specification artifacts. Only simulation can give the business customer real awareness that product specification correctly defines all his needs.
Simulation prototype with mockup data should be as realistic as possible, so the business customer can really give all his remarks, pinpoint all his needs, before the developers start to write code. And they can say - Yes this is exactly what I want!
On the other hand for developers is much easier to start to code when they see Simulation prototype with some mockup data or real production data, before the developers start to write code.

The early simulation is revolutionizing the whole process. What that future solution could look like prior to actually entering in the software design and coding stage.
The real difference is that:
- you can make the Walk-through of the future solution
- production scenarios can be tested
- real production data can be used to simulate the workflow step by step
- so the implementation errors can be avoided
- business customer will be confident that the solution will meet his requirements
- faster development cycles
- fewer surprises in end-user testing
- in rework phase there is a significant reduction
- the totality of effort and cost will be reduced
- more than 60% reduction in change orders

* Move effortlessly between requirements management, behavior modeling and simulation, physical architecture modeling, verification requirements and test plans in one integrated and consistent project model
* Automatically generate specifications and requirements traceability matrices quickly and confidently at any point throughout a project with confidence that your documents represent the most current data

In the past functional design document was often used to pinpoint who made mistake if something did not work at the end, and it was frustrating and conflicting, while simulation will avoid errors and ambiguities which can occur in a 1000 pages word document.

Not everyone involved design & development process can be a risk expert, but everyone will suffer if the risk is not managed proactively upfront. It is important to consider risk management by integrating risk elements within end-to-end work process and providing customizable structured worksheet formats based on traditional risk management approaches like FMEA, FMECA, Hazard Analysis, etc. The templates are straight out of the guidebooks and can be customized to match the unique QA, regulatory, and product type needs of any business.
Poorly defined requirements, complaining, and excessive oversight from senior management, are all contributors to scope instability and excessive changes. All projects will experience change. The purpose of change control is not to prevent changes, but rather, to ensure that changes are captured, evaluated and approved with they are “good” for the project. Even with a robust, effective change control process it is difficult to maintain scope stability when change requests are constant and often from unexpected (unrecognized) sources.
Solution should be as intuitive and as flexible as possible, so that training should be potentially eliminated, or at least reduced.

Overview
The market for Requirement Management (RM) tools looks heavily over-saturated, but new players still constantly enter: all the more remarkable given globally difficult trading conditions. Needless to say, other players quietly vanish from the market, another half-dozen went in 2014. Free trials are becoming universal for new tools, and prices for web-based software are falling. There is a widening gap between the heavyweight, closed environment, local database, all-under-one-roof traditional RM tools, and the lighter, cheaper, web-based tools offering free integrations with other software.

Trends

Low-cost or simply free tools are steadily coming on to the market. Each one chips away at the market perception that a pricey system which ties you into one supplier is necessary. Tools making this trend include Axiom, Banana Scrum, DESIRe, Avenqo PEP, iRise, jUCMNav, LiteRM, OneDesk, ReqT, RMtoo, Scrumwise, TrackStudio, TREND/Analyst. Others are constantly appearing.
On-Demand, Online
Requirements tools are becoming simple to install, needing no system administration, and much cheaper, at least up front. This is achieved by keeping the data online, accessed by a browser application (just as Google is doing for ordinary office software). Of course this also enables more mobile access.
Tools making this trend include Accompa and TopTeam Analyst.
Open Source, Open Data
Back in 2001 at the RE conference I found myself (by surprise) on a Future of RM Tools panel. I predicted that tools would move from the large, costly, monolithic, closed model towards a more open world where third-party tools could process RM data, e.g. for analysis, graphing, code generation or test planning. It has taken a long time, but finally in 2011 there appeared RM tools that are small, cheap or free, with open data, or even open source code.
Tools making this trend include RMtoo (open source, open data), and in a very different way DOORS (open data exchange with RIF, an industry-standard XML format for requirements).