How to get a list of built-in modules in python?


I would like to get a list of names of built-in modules in python such that I can test the popularity of function’s naming conventions (underline, CamelCase or mixedCase).

I know there is a Global Module Index but I am wondering if there is a list of strings, which is easier to use 🙂


len(dir(__builtins__)) = 145  
len(stdlib_list("2.7")) = 430  
help('modules') = 508 # counting manually the output
Asked By: Drake Guan



How about this? Though, this gets a list of built-in functions and variables rather than modules…


help('modules') will give you a list of all modules, according to How can I get a list of locally installed Python modules?. Not a list of strings, though.

Answered By: U-DON

The compiled-in module names are in sys.builtin_module_names. For all importable modules, see pkgutil.iter_modules.

Run these in a clean virtualenv to get (almost) only the modules that come with Python itself.

Note that a “popularity poll” will necessarily include modules that use old, discouraged naming conventions because they were written before today’s guidelines were put in place, and can’t change because need to be backwards compatible. It might be useful for something, but not for answering best-practice questions such as “How should I name my functions?”. For that, see the PEP8, the Python style guide, especially the “Naming Conventions” section.

Answered By: Petr Viktorin

>>>dir (__builtins__)


>>>help (__builtins__)

Answered By:

Now there is a 3rd party package for this. It scrapes the TOC of the Standard Library page in the official Python docs and builds a list.

You can install it using pip

pip install stdlib_list

and got get a list of libraries

In [12]: from stdlib_list import stdlib_list

In [13]: libraries = stdlib_list("3.5")

In [14]: libraries[4:12]
Out[14]: ['abc', 'aifc', 'argparse', 'array', 'ast', 'asynchat', 'asyncio', 'asyncore']

You can find source code here.

Answered By: Chillar Anand

From the CPython`s docs:

All known built-in modules are listed in sys.builtin_module_names

Names of modules in sys.builtin_module_names is actual only for used a Python interpreter:

A tuple of strings giving the names of all modules that are compiled into this Python interpreter

Each built-in module use the special loader while importing: BuiltinImporter

In [65]: import itertools, sys, gc

In [66]: itertools.__loader__, sys.__loader__, gc.__loader__

In the Python 3 the number of built-in modules has slightly increased

$ python2.7 -c "import sys; print('Count built-in modules: %d' %len(sys.builtin_module_names)); print(sys.builtin_module_names)"
Count built-in modules: 51
('__builtin__', '__main__', '_ast', '_bisect', '_codecs', '_collections', '_functools', '_heapq', '_io', '_locale', '_md5', '_random', '_sha', '_sha256', '_sha512', '_socket', '_sre', '_struct', '_symtable', '_warnings', '_weakref', 'array', 'binascii', 'cPickle', 'cStringIO', 'cmath', 'datetime', 'errno', 'exceptions', 'fcntl', 'gc', 'grp', 'imp', 'itertools', 'marshal', 'math', 'operator', 'posix', 'pwd', 'select', 'signal', 'spwd', 'strop', 'sys', 'syslog', 'thread', 'time', 'unicodedata', 'xxsubtype', 'zipimport', 'zlib')
$ python3.4 -c "import sys; print('Count built-in modules: %d' %len(sys.builtin_module_names)); print(sys.builtin_module_names)"
Count built-in modules: 54
('_ast', '_bisect', '_codecs', '_collections', '_datetime', '_elementtree', '_functools', '_heapq', '_imp', '_io', '_locale', '_md5', '_operator', '_pickle', '_posixsubprocess', '_random', '_sha1', '_sha256', '_sha512', '_socket', '_sre', '_stat', '_string', '_struct', '_symtable', '_thread', '_tracemalloc', '_warnings', '_weakref', 'array', 'atexit', 'binascii', 'builtins', 'errno', 'faulthandler', 'fcntl', 'gc', 'grp', 'itertools', 'marshal', 'math', 'posix', 'pwd', 'pyexpat', 'select', 'signal', 'spwd', 'sys', 'syslog', 'time', 'unicodedata', 'xxsubtype', 'zipimport', 'zlib')

As the CPython is implemented (primary) on the C programming language, so it is not easy to find it, as example location the Python`s module sys (based on this answer):

$ locate sysmodule | grep python

More information about getting an information about all available modules is the CPython, look in my answer here.

Answered By: PADYMKO

It can be done using the given block of code below and it is the most effective way as per me.

import sys
a = sys.builtin_module_names

The last line to be included if you want to print them.
Here, a is a tuple and so it can access all the functionalities of a tuple.

You can have a look at sys.builtin_module_names for further help

Answered By: Akash Kumar

I was working on a similar problem when I learned that ‘builtin’ means something like "there is no source file associated with this object".

Here’s a solution based on checking the /lib and /Dlls folders manually.
The use of "unique" may be redundant; it’s there because I’m not sure if DLLs is strictly for packages which come with python/it was useful for a different problem I was trying to solve (finding out the requirements for a source package).

from typing import Generator, Iterable
import os, re, sys

def unique(iterable:Iterable, yielded_list=None) -> Generator:
    Iterate over unique elements of an iterable
        >>> [*unique('abbcccdddd')]
        ['a', 'b', 'c', 'd']
        >>> [*unique('abcd')]
        ['a', 'b', 'c', 'd']
    yielded = yielded if not isinstance(yielded, type(None)) else []
    for i in iterable:
        if not i in yielded:
            yield i

def native_modules() -> Generator:
    Every module found:
        under your installation's /lib and /DLLs directories; excuding any under /lib/site-packages/*
        in sys.builtin_module_names
    omitables = 'site-packages __pycache__ .pyo .ico .dll .pdb'.split()
    path = lambda folder: os.path.join(sys.exec_prefix, folder)
    tidy = lambda pth: os.path.split(os.path.splitext(pth)[0])[-1] # separate the name from the path and extension, if present
    discriminant = lambda pth: not any(re.match(i, pth) for i in map(re.escape, omitables))
    lib = map(tidy, filter(discriminant, os.listdir(path('lib'))))
    dlls = map(tidy, filter(discriminant, os.listdir(path('DLLs'))))

    yielded = []
    yield from yielded
    yield from unique(sys.builtin_module_names, yielded)
    yield from unique(lib, yielded)
    yield from unique(dlls, yielded)
Answered By: kendfss

All the commands like dir(builtins) or help(builtins) or sys.builtin_module_names, are either missing several core inbuilt package names or giving thousands of lines of verbose output.

>>> help(‘modules’)

The best command to show all the installed modules is help(‘modules’). It gives you name of all the installed modules in python without missing anything.

Incase you need names of inbuilt modules only, create a temporary fresh venev and give the command there. It might be bit slow but is the only way by far in my experience to list every single package.

Answered By: Vaibhav VK

In Linux, you can get a dump of all the built-in modules that came with the fresh install with the following commands

sudo apt-get install python3-virtualenv

tmpDir=`mktemp -d`

python3 -m virtualenv $tmpDir
source /tmp/virtualenv/bin/activate


Example Execution

Here’s an example execution of the above commands in Debian 11 with python 3.9

[email protected]:~$ sudo apt-get install python3-virtualenv
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
python3-virtualenv is already the newest version (20.4.0+ds-2+deb11u1).
The following packages were automatically installed and are no longer required:
  ethtool libbotan-2-17 libtspi1 linux-image-5.10.0-10-amd64
  linux-image-5.10.0-13-amd64 linux-image-5.10.0-14-amd64
  linux-image-5.10.0-15-amd64 linux-image-5.10.0-16-amd64
  linux-image-5.10.0-17-amd64 net-tools sse3-support
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.
[email protected]:~$ 

[email protected]:~$ tmpDir=`mktemp -d`
[email protected]:~$ 

[email protected]:~$ python3 -m virtualenv $tmpDir
created virtual environment in 120ms
  creator CPython3Posix(dest=/tmp/tmp.qQsKZHGZqk, clear=False, no_vcs_ignore=False, global=False)
  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=/home/user/.local/share/virtualenv)
    added seed packages: pip==20.3.4, pkg_resources==0.0.0, setuptools==44.1.1, wheel==0.34.2
  activators BashActivator,CShellActivator,FishActivator,PowerShellActivator,PythonActivator,XonshActivator
[email protected]:~$ source /tmp/virtualenv/bin/activate
(virtualenv) [email protected]:~$ python
Python 3.9.2 (default, Feb 28 2021, 17:03:44) 
[GCC 10.2.1 20210110] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> help('modules')

Please wait a moment while I gather a list of all available modules...

__future__          _tracemalloc        graphlib            retrying
_abc                _uuid               grp                 rlcompleter
_aix_support        _virtualenv         gzip                runpy
_ast                _warnings           hashlib             sched
_asyncio            _weakref            heapq               secrets
_bisect             _weakrefset         hmac                select
_blake2             _xxsubinterpreters  html                selectors
_bootlocale         _xxtestfuzz         html5lib            setuptools
_bootsubprocess     _zoneinfo           http                shelve
_bz2                abc                 idna                shlex
_codecs             aifc                imaplib             shutil
_codecs_cn          antigravity         imghdr              signal
_codecs_hk          appdirs             imp                 site
_codecs_iso2022     argparse            importlib           sitecustomize
_codecs_jp          array               inspect             smtpd
_codecs_kr          ast                 io                  smtplib
_codecs_tw          asynchat            ipaddr              sndhdr
_collections        asyncio             ipaddress           socket
_collections_abc    asyncore            itertools           socketserver
_compat_pickle      atexit              json                spwd
_compression        audioop             keyword             sqlite3
_contextvars        base64              lib2to3             sre_compile
_crypt              bdb                 linecache           sre_constants
_csv                binascii            locale              sre_parse
_ctypes             binhex              logging             ssl
_ctypes_test        bisect              lzma                stat
_curses             builtins            mailbox             statistics
_curses_panel       bz2                 mailcap             string
_datetime           cProfile            marshal             stringprep
_dbm                calendar            math                struct
_decimal            certifi             mimetypes           subprocess
_elementtree        cgi                 mmap                sunau
_functools          cgitb               modulefinder        symbol
_hashlib            chunk               msgpack             symtable
_heapq              cmath               multiprocessing     sys
_imp                cmd                 netrc               sysconfig
_io                 code                nis                 syslog
_json               codecs              nntplib             tabnanny
_locale             codeop              ntpath              tarfile
_lsprof             collections         nturl2path          telnetlib
_lzma               colorama            numbers             tempfile
_markupbase         colorsys            opcode              termios
_md5                compileall          operator            test
_multibytecodec     concurrent          optparse            textwrap
_multiprocessing    configparser        os                  this
_opcode             contextlib          ossaudiodev         threading
_operator           contextlib2         packaging           time
_osx_support        contextvars         parser              timeit
_peg_parser         copy                pathlib             tkinter
_pickle             copyreg             pdb                 token
_posixshmem         crypt               pep517              tokenize
_posixsubprocess    csv                 pickle              toml
_py_abc             ctypes              pickletools         trace
_pydecimal          curses              pip                 traceback
_pyio               dataclasses         pipes               tracemalloc
_queue              datetime            pkg_resources       tty
_random             dbm                 pkgutil             turtle
_sha1               decimal             platform            types
_sha256             difflib             plistlib            typing
_sha3               dis                 poplib              unicodedata
_sha512             distlib             posix               unittest
_signal             distutils           posixpath           urllib
_sitebuiltins       doctest             pprint              urllib3
_socket             easy_install        profile             uu
_sqlite3            email               progress            uuid
_sre                encodings           pstats              venv
_ssl                enum                pty                 warnings
_stat               errno               pwd                 wave
_statistics         faulthandler        py_compile          weakref
_string             fcntl               pyclbr              webbrowser
_strptime           filecmp             pydoc               wheel
_struct             fileinput           pydoc_data          wsgiref
_symtable           fnmatch             pyexpat             xdrlib
_sysconfigdata__linux_x86_64-linux-gnu formatter           pyparsing           xml
_sysconfigdata__x86_64-linux-gnu fractions           queue               xmlrpc
_testbuffer         ftplib              quopri              xxlimited
_testcapi           functools           random              xxsubtype
_testimportmultiple gc                  re                  zipapp
_testinternalcapi   genericpath         readline            zipfile
_testmultiphase     getopt              reprlib             zipimport
_thread             getpass             requests            zlib
_threading_local    gettext             resolvelib          zoneinfo
_tkinter            glob                resource            

Enter any module name to get more help.  Or, type "modules spam" to search
for modules whose name or summary contain the string "spam".

Answered By: Michael Altfield
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