This paper presents a timed coloured Petri nets based programming tool that supports modeling and performance analysis of distributed World Wide Web environments. A distributed Internet system model, initially described in compliance with queueing theory (QT) rules, is mapped onto the Timed coloured petri net (TCPN) structure by means of queueing system templates. Then, it is executed and analyzed using design/CPN toolset. The proposed distributed Internet systems modeling and design methodology has been applied for evaluation of several system architectures under different external loads.