This paper describes a web-based tool that supports the modeling and design of abstract unit-load picking systems.  The term “abstract” implies that the model is not specific to any equipment or vendors’ products, but, instead, focuses on the generic system components such as pallets, racks, slots, forklifts, cranes, etc. that comprise typical unit load picking systems.  The objectives of the tool are to support the design of an AS/RS based or a manual forklift-based picking system based on a set of design parameters and to be able to convert from an AS/RS design to a flat warehouse design and vice versa.  The research objective is to design the formal model (the data structure and operational description) that supports the conversion from one type to the other and supports the generation of static and dynamic analysis models and the recording of the analysis results.  The web implementation uses a mix of XML, HTML, JavaScript and PHP and implements two existing analysis methodologies from the literature.