The Common Gateway Interface, or CGI, is a methodology whereby programs run on a server which coordinates the flow of information between the client web browser and said programs. Most CGI solutions are developed in Perl, with a minority developed in C or C++. While it is very rarely seen in new solutions, there are many mid 1990s legacy solutions based on this platform.

The precursor to Microsoft's ASP.NET platform, ASP 3.0, or "Classic ASP" as it's sometimes referred to, is no longer supported as an active platform by Microsoft. This means that no new "patches" or "upgrades" will be released, and new servers will only support it in a special mode which does not allow interaction at the level of new technologies.

Software consulting firms developing on these platforms should be looked at with a scrutinizing eye by any potential client. These platforms have experienced widespread success in the mid 1990s, but since then are all but deprecated for the development of new solutions.

Ruby on Rails is a web platform that is currently in the minority, but is gaining traction with developers who like the flexibility of PHP, but are disappointed with the elegance of typical PHP solutions. Ruby is a powerful language which offers software developers elegant solutions which are also highly performant and can be developed rapidly.

These platforms represent less than 5% of web applications built today. Firms building solutions on these platforms are most likely smaller and very specialized. A warning when considering minor platforms: the market leading platforms are leading for a reason - they represent the most vetted, long-lasting investments for the client. That said, "new and upcoming" platforms can be a fit as long as the software consultants are very familiar with them and are not using your project as a chance to "learn something cool".