The REBOL Technologies main product is named REBOL/Core. It is an application engine that insulates REBOL applications from operating system dependencies. The engine executes scripts written in a new messaging language called REBOL (Relative Expression-Based Object Language). It is designed to support the construction of complex distributed applications that require Internet access. The REBOL application engine features a graphical display engine.

REBOL/Core consists of the application engine, Internet protocol support, language interpreter and basic console. The primary function of REBOL/Core is to serve as a development and execution tool for all REBOL applications. REBOL/Core is available as a free download, to encourage the adoption and use of REBOL applications, and to promote knowledge of the REBOL language and application engine. For more information, see www.rebol.com.