The company's first product was Citrix Multiuser, an extension of OS/2 developed over two years. Citrix licensed the OS/2 source code from Microsoft, and developed its own Independent Computing Architecture (ICA) protocol for Citrix Multiuser. Multiuser allowed multiple users working on separate computers remote access to software on a server, even from computers not built to run OS/2. Three days before the product launched in 1991, Microsoft announced they would be switching from OS/2 to Windows. The switch made Multiuser nearly unusable without significant changes to make it compatible with Windows or DOS. The company discussed closing in 1991, but investments from Intel, Microsoft and Kleiner Perkins Caufield & Byers among others, allowed the company to work on a new version of Multiuser.