Simulators, emulators and testbeds are invaluable tools for performance evaluation of algorithms and protocols in wireless sensor networks (WSNs). It is extremely difficult to choose an appropriate tool for performance testing without the horizontal and vertical analysis of existing tools. This paper presents a survey of thirty five performance evaluation tools for WSNs. Unlike most other studies, tools were selected based on their popularity, support for WSNs, active maintenance and the help available. On the horizontal dimension, prominent competitors at each stage were selected. For vertical analysis, tools for simulation, emulation and testbeds were categorized accordingly. We believe that this survey will aid researchers, application and tool developers while selecting an appropriate tool for their implementation. We have highlighted an open research issue to have an integrated tool that supports modeling, simulation, emulation and testbed implementation for algorithm validation, performance evaluation and proof-of-concept implementation in WSNs. © 2010 IEEE.