For the assessment of the thermal performance of heat pipes, a wide range of modeling is available in the literature, ranging from simple capillary limit analyses to comprehensive 3D models. While simplistic models may result in less accurate predictions of heat transfer and operating temperatures, comprehensive models may be computationally expensive. In this study, a universal computational framework is developed for a fast but sufficiently accurate modeling of traditional heat pipes, and an analysis tool based on this framework, named Heat Pipe Analysis Toolbox, in short H-PAT is presented. As a diagnostic tool, H-PAT can predict the fluid flow and heat transfer from a heat pipe under varying heat inputs up to the onset of dryout. During the initial estimation of phase change rates, the solutions of particular thin film phase change models are avoided by specifying an appropriate pattern for the mass flow rate of the liquid along the heat pipe rather than using finite element/volume based methods for the computational domain. With the help of a modular structure, H-PAT can simulate heat pipes with different wick structures as long as an expression for the average liquid velocity and corresponding pressure drop can be introduced. H-PAT is also capable of analyzing heat pipes with variable cross-sections, favorable/unfavorable gravity conditions and utilizes temperature dependent thermo-physical properties at evaporator, condenser and adiabatic regions together with heat input sensitive vapor pressure. In addition, H-PAT performs the computation very fast which also makes it a perfect design tool for researchers and design engineers in the field of thermal management.