less robust than cpythonthoughit is usually seen as tool of interest primarily to java developers looking for scripting language to serve as frontend to java code see jython' website ironpythonpython for net third implementation of pythonand newer than both cpython and jythonironpython is designed to allow python programs to integrate with applications coded to work with microsoft' net framework for windowsas well as the mono open source equivalent for linux net and its cprogramming language runtime system are designed to be language-neutral object communication layerin the spirit of microsoft' earlier com model ironpython allows python programs to act as both client and server componentsgain accessibility both to and from other net languagesand leverage net technologies such as the silverlight framework from their python code by implementationironpython is very much like jython (andin factwas developed by the same creator)--it replaces the last two bubbles in figure - with equivalents for execution in the net environment also like jythonironpython has special focus --it is primarily of interest to developers integrating python with net components formerly developed by microsoft and now an open source projectironpython might also be able to take advantage of some important optimization tools for better performance for more detailsconsult with web search stacklesspython for concurrency still other schemes for running python programs have more focused goals for examplethe stackless python system is an enhanced version and reimplementation of the standard cpython language oriented toward concurrency because it does not save state on the language call stackstackless python can make python easier to port to small stack architecturesprovides efficient multiprocessing optionsand fosters novel programming structures such as coroutines among other thingsthe microthreads that stackless adds to python are an efficient and lightweight alternative to python' standard multitasking tools such as threads and processesand promise better program structuremore readable codeand increased programmer productivity ccp gamesthe creator of eve onlineis well-known stackless python userand compelling python user success story in general try http//stackless com for more information pypypython for speed the pypy system is another standard cpython reimplementationfocused on performance it provides fast python implementation with jit (just-in-timecompilerprovides tools for "sandboxmodel that can run untrusted code in secure environexecution model variations