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Python 3.3.5

Python 3.3.5 release candidate 1 was released on February 23th, 2014. This release fixes a regression with the zipimport functionality in 3.3.4 and several other bugs found in Python 3.3.4.

This release fully supports OS X 10.9 Mavericks. In particular, this release fixes an issue that could cause previous versions of Python to crash when typing in interactive mode on OS X 10.9.

Major new features of the 3.3 series, compared to 3.2

Python 3.3 includes a range of improvements of the 3.x series, as well as easier porting between 2.x and 3.x.

  • PEP 380, syntax for delegating to a subgenerator (yield from)
  • PEP 393, flexible string representation (doing away with the distinction between "wide" and "narrow" Unicode builds)
  • A C implementation of the "decimal" module, with up to 120x speedup for decimal-heavy applications
  • The import system (__import__) is based on importlib by default
  • The new "lzma" module with LZMA/XZ support
  • PEP 397, a Python launcher for Windows
  • PEP 405, virtual environment support in core
  • PEP 420, namespace package support
  • PEP 3151, reworking the OS and IO exception hierarchy
  • PEP 3155, qualified name for classes and functions
  • PEP 409, suppressing exception context
  • PEP 414, explicit Unicode literals to help with porting
  • PEP 418, extended platform-independent clocks in the "time" module
  • PEP 412, a new key-sharing dictionary implementation that significantly saves memory for object-oriented code
  • PEP 362, the function-signature object
  • The new "faulthandler" module that helps diagnosing crashes
  • The new "unittest.mock" module
  • The new "ipaddress" module
  • The "sys.implementation" attribute
  • A policy framework for the email package, with a provisional (see PEP 411) policy that adds much improved unicode support for email header parsing
  • A "collections.ChainMap" class for linking mappings to a single unit
  • Wrappers for many more POSIX functions in the "os" and "signal" modules, as well as other useful functions such as "sendfile()"
  • Hash randomization, introduced in earlier bugfix releases, is now switched on by default


This is a preview release, and its use is not recommended in production settings.

We support these formats for download:

The source tarballs are signed with Georg Brandl's key, which has a key id of 36580288; the fingerprint is 26DE A9D4 6133 91EF 3E25 C9FF 0A5B 1018 3658 0288. The Windows installer was signed by Martin von Lรถwis' public key, which has a key id of 7D9DC8D2. The Mac installers were signed with Ned Deily's key, which has a key id of 6F5E1540. The public keys are located on the download page.

MD5 checksums and sizes of the released files:

f5385c4c809072b1c5b49d5faae4f9b2  16876611  Python-3.3.5rc1.tgz
91afd237a2e378476c6d4616b2a69dda  12103472  Python-3.3.5rc1.tar.xz
8ab7ec6d3e81ead6b3578f6bf75810d9  19963194  python-3.3.5rc1-macosx10.5.dmg
60aaf53e0ebb5a7ecd2349f212c62835  20017628  python-3.3.5rc1-macosx10.6.dmg
539cfc3b15ce42603bfaadd471e9c158  27050536
dbf4d1947d37fbd05b20f1d84dacc102  22153590
97bb3692b165df901b1e72226d413fe6  21209088  python-3.3.5rc1.amd64.msi
981592c6735608d584ab871ae0714f80  20660224  python-3.3.5rc1.msi
d8993436235be56dfddc304f0c1d6237   6708839  python335rc1.chm
[1]The binaries for AMD64 will also work on processors that implement the Intel 64 architecture (formerly EM64T), i.e. the architecture that Microsoft calls x64, and AMD called x86-64 before calling it AMD64. They will not work on Intel Itanium Processors (formerly IA-64).
[2](1, 2) There is important information about IDLE, Tkinter, and Tcl/Tk on Mac OS X here.