Pympler is a development tool to measure, monitor and analyze the memory behavior of Python objects in a running Python application. By pympling a Python application, detailed insight in the size and the lifetime of Python objects can be obtained. Undesirable or unexpected runtime behavior like memory bloat and other "pymples" can easily be identified. Pympler integrates three previously separate projects into a single, comprehensive profiling tool. Asizeof provides basic size information for one or several Python objects, muppy is used for on-line monitoring of a Python application and the class tracker provides off-line analysis of the lifetime of selected Python objects. A web profiling frontend exposes process statistics, garbage visualisation and class tracker statistics. Pympler is written entirely in Python, with no dependencies to external libraries on Linux and MacOS. On Windows, pywin32 is required.