This package will install Python $FULL_VERSION for macOS $MACOSX_DEPLOYMENT_TARGET for the following architecture(s): $ARCHITECTURES.

Which installer variant should I use? [CHANGED in 2.7.15]

**NEW** With Python 2.7.15, the python.org website now provides two installer variants for download: one that installs a 64-bit-only Python capable of running on macOS 10.9 (Mavericks) or later; and one that installs a 64-bit/32-bit Intel Python capable of running on macOS 10.6 (Snow Leopard) or later.  (This ReadMe was installed with the $MACOSX_DEPLOYMENT_TARGET variant.)  Previous Python 2.7.x releases provided the 10.6 or later installer and a 10.5 or later 32-bit-only variant. If you are running on macOS 10.9 or later and if you have no need for compatibility with older systems, use the 10.9 variant.  Use the 10.6 variant if you are running on macOS 10.6 through 10.8, if you need to maintain compatibility with previous 2.7.x releases, or if you want to produce standalone applications that can run on systems from 10.6.  The Pythons installed by these installers are built with private copies of some third-party libraries not included with or newer than those in macOS itself.  The list of these libraries varies by installer variant and is included at the end of the License.rtf file.

Certificate verification and OpenSSL_[CHANGED in 2.7.15]

This variant of Python 2.7 now includes its own private copy of OpenSSL 1.0.2.  Unlike previous releases, the deprecated Apple-supplied OpenSSL libraries are no longer used.  This also means that the trust certificates in system and user keychains managed by the Keychain Access application and the security command line utility are no longer used as defaults by the Python ssl module.  A sample command script is included in /Applications/Python 2.7 to install a curated bundle of default root certificates from the third-party certifi package (https://pypi.python.org/pypi/certifi).  Click on Install Certificates to run it.  If you choose to use certifi, you should consider subscribing to the project's email update service to be notified when the certificate bundle is updated.

The bundled pip included with the Python 2.7 installer has its own default certificate store for verifying download connections.

Using IDLE or other Tk applications [NEW/CHANGED in 2.7.15] 

The 10.9+ installer variant comes with its own private version of Tcl/Tk 8.6. It does not use system-supplied or third-party supplied versions of Tcl/Tk.

For the 10.6+ variant, you continue to need to install a newer third-party version of the Tcl/Tk 8.5 (not 8.6) frameworks to use IDLE or other programs that use the Tkinter graphical user interface toolkit.  Visit https://www.python.org/download/mac/tcltk/ for current information about supported and recommended versions of Tcl/Tk for this version of Python and of macOS.

Binary installer support for Mac OS X 10.5 and earlier discontinued [CHANGED for Python 2.7.15]

As of Python 2.7.15, binary installers from python.org no longer support Mac OS X 10.5 (Leopard) systems.   Binary installer support for Mac OS X 10.3.9 (Panther) and 10.4.x (Tiger) systems was previously dropped in Python 2.7.9.  Mac OS X 10.5 was originally released by Apple in 2007 and last updated in 2009 and was the last OS X release for PPC machines (G4 and G5).  If needed, it is still possible to build Python from source for 10.3.9, 10.4, or 10.5.

Packages installed with the system Python 2.7 are no longer searched for [CHANGED for Python 2.7.13]

As of Python 2.7.0, user-installed Python 2.7 versions from python.org installers added the system-wide site-packages directory for the Apple-supplied Python 2.7 to the end of their search path.  This meant that packages installed with the system Python 2.7 could also be used by the user-installed Python 2.7.  While sometimes convenient, this also often caused confusion with the implicit coupling between the two Python instances.  Separately, as of macOS 10.12, Apple changed the layout of the system site-packages directory, /Library/Python/2.7/site-packages, in a way that can now cause installation of pip components to fail.  To avoid the confusion and the installation failures, as of 2.7.13 user-installed Pythons no longer add /Library/Python/2.7/site-packages to sys.path.  If you are using a package with both a user-installed Python 2.7 and the system Python 2.7, you will now need to ensure that separate copies of the package are installed for each instance.

Installing on OS X 10.8 (Mountain Lion) or later systems [CHANGED for Python 2.7.9]

As of Python 2.7.9, installer packages from python.org are now compatible with the Gatekeeper security feature introduced in OS X 10.8.   Downloaded packages can now be directly installed by double-clicking with the default system security settings.  Python.org installer packages for macOS are signed with the Developer ID of the builder, as identified on the download page for this release.  To inspect the digital signature of the package, click on the lock icon in the upper right corner of the Install Python installer window.  Refer to Apple’s support pages for more information on Gatekeeper.

Simplified web-based installs [NEW for Python 2.7.9]

With the change to the newer flat format installer package, the download file now has a .pkg extension as it is no longer necessary to embed the installer within a disk image (.dmg) container.   If you download the Python installer through a web browser, the macOS installer application may open automatically to allow you to perform the install.  If your browser settings do not allow automatic open, double click on the downloaded installer file.

New Installation Options and Defaults [NEW for Python 2.7.9]

The Python installer now includes an option to automatically install or upgrade pip, a tool for installing and managing Python packages.  This option is enabled by default and no Internet access is required.  If you do not want the installer to do this, select the Customize option at the Installation Type step and uncheck the Install or upgrade pip option.  For other changes in this release, see the Release Notes link for this release at https://www.python.org/downloads/.

Python 3 and Python 2 Co-existence

Python.org Python 2.7 and 3.x versions can both be installed on your system and will not conflict.  Python 2.7 command names contain a 2 or no digit: python2 (or python2.7 or python), idle2 (or idle2.7 or idle), pip2 (or pip2.7 or pip), etc.  Command names for Python 3 contain a 3 in them, python3, idle3, pip3, etc.  Also, installing a python.org Python 2.7 does not alter or remove any Apple-supplied system Pythons, found in /usr/bin.