The paper presents a software tool that demonstrates principles of RAM memory testing and of the memory BIST structure. The MemBIST software tool automatically generates built-in self-test blocks for a given memory matrix as a VHDL model of the whole system. As a complement to the BIST structure generator, a module for visualisation of selected RAM memory fault models, March C- test algorithm as well as a memory self-testing architecture principle is a part of the tool. The developed system was implemented as a Java applet what means its good compatibility regarding different hardware and operating system platforms, its safety and accessibility while it is placed on Internet. The presented MemBIST applet is useful as an educational tool and a training tool in built-in selftesting for RAM memories.