The Python Standard Library

While The Python Language Reference describes the exact syntax and semantics of the Python language, this library reference manual describes the standard library that is distributed with Python. It also describes some of the optional components that are commonly included in Python distributions.

Pythons standard library is very extensive, offering a wide range of facilities as indicated by the long table of contents listed below. The library contains built-in modules (written in C) that provide access to system functionality such as file I/O that would otherwise be inaccessible to Python programmers, as well as modules written in Python that provide standardized solutions for many problems that occur in everyday programming. Some of these modules are explicitly designed to encourage and enhance the portability of Python programs by abstracting away platform-specifics into platform-neutral APIs.

The Python installers for the Windows platform usually include the entire standard library and often also include many additional components. For Unix-like operating systems Python is normally provided as a collection of packages, so it may be necessary to use the packaging tools provided with the operating system to obtain some or all of the optional components.

In addition to the standard library, there is an active collection of hundreds of thousands of components (from individual programs and modules to packages and entire application development frameworks), available from the Python Package Index.

• Introduction
  • Notes on availability
• Built-in Functions
• Built-in Constants
  • Constants added by the site module
• Built-in Types
  • Truth Value Testing
  • Boolean Operations and, or, not
  • Comparisons
  • Numeric Types int, float, complex
  • Boolean Type - bool
  • Iterator Types
  • Sequence Types list, tuple, range
  • Text and Binary Sequence Type Methods Summary
  • Text Sequence Type str
  • Binary Sequence Types bytes, bytearray, memoryview
  • Set Types set, frozenset
  • Mapping Types dict
  • Context Manager Types
  • Type Annotation Types Generic Alias, Union
  • Other Built-in Types
  • Special Attributes
  • Integer string conversion length limitation
• Built-in Exceptions
  • Exception context
  • Inheriting from built-in exceptions
  • Base classes
  • Concrete exceptions
  • Warnings
  • Exception groups
  • Exception hierarchy
• Thread Safety Guarantees
  • Thread safety levels
  • Thread safety for list objects
  • Thread safety for dict objects
  • Thread safety for set objects
  • Thread safety for bytearray objects
  • Thread safety for memoryview objects
• Text Processing Services
  • string Common string operations
  • string.templatelib Support for template string literals
  • re Regular expression operations
  • difflib Helpers for computing deltas
  • textwrap Text wrapping and filling
  • unicodedata Unicode Database
  • stringprep Internet String Preparation
  • readline GNU readline interface
  • rlcompleter Completion function for GNU readline
• Binary Data Services
  • struct Interpret bytes as packed binary data
  • codecs Codec registry and base classes
• Data Types
  • datetime Basic date and time types
  • zoneinfo IANA time zone support
  • calendar General calendar-related functions
  • collections Container datatypes
  • collections.abc Abstract Base Classes for Containers
  • heapq Heap queue algorithm
  • bisect Array bisection algorithm
  • array Efficient arrays of numeric values
  • weakref Weak references
  • types Dynamic type creation and names for built-in types
  • copy Shallow and deep copy operations
  • pprint Data pretty printer
  • reprlib Alternate repr() implementation
  • enum Support for enumerations
  • graphlib Functionality to operate with graph-like structures
• Numeric and Mathematical Modules
  • numbers Numeric abstract base classes
  • math Mathematical functions
  • cmath Mathematical functions for complex numbers
  • decimal Decimal fixed-point and floating-point arithmetic
  • fractions Rational numbers
  • random Generate pseudo-random numbers
  • statistics Mathematical statistics functions
• Functional Programming Modules
  • itertools Functions creating iterators for efficient looping
  • functools Higher-order functions and operations on callable objects
  • operator Standard operators as functions
• File and Directory Access
  • pathlib Object-oriented filesystem paths
  • os.path Common pathname manipulations
  • stat Interpreting stat() results
  • filecmp File and Directory Comparisons
  • tempfile Generate temporary files and directories
  • glob Unix style pathname pattern expansion
  • fnmatch Unix filename pattern matching
  • linecache Random access to text lines
  • shutil High-level file operations
• Data Persistence
  • pickle Python object serialization
  • copyreg Register pickle support functions
  • shelve Python object persistence
  • marshal Internal Python object serialization
  • dbm Interfaces to Unix databases
  • sqlite3 DB-API 2.0 interface for SQLite databases
• Data Compression and Archiving
  • The compression package
  • compression.zstd Compression compatible with the Zstandard format
  • zlib Compression compatible with gzip
  • gzip Support for gzip files
  • bz2 Support for bzip2 compression
  • lzma Compression using the LZMA algorithm
  • zipfile Work with ZIP archives
  • tarfile Read and write tar archive files
• File Formats
  • csv CSV File Reading and Writing
  • configparser Configuration file parser
  • tomllib Parse TOML files
  • netrc netrc file processing
  • plistlib Generate and parse Apple .plist files
• Cryptographic Services
  • hashlib Secure hashes and message digests
  • hmac Keyed-Hashing for Message Authentication
  • secrets Generate secure random numbers for managing secrets
• Generic Operating System Services
  • os Miscellaneous operating system interfaces
  • io Core tools for working with streams
  • time Time access and conversions
  • logging Logging facility for Python
  • logging.config Logging configuration
  • logging.handlers Logging handlers
  • platform Access to underlying platforms identifying data
  • errno Standard errno system symbols
  • ctypes A foreign function library for Python
• Command-line interface libraries
  • argparse Parser for command-line options, arguments and subcommands
  • optparse Parser for command line options
  • getpass Portable password input
  • fileinput Iterate over lines from multiple input streams
  • curses Terminal handling for character-cell displays
  • curses.textpad Text input widget for curses programs
  • curses.ascii Utilities for ASCII characters
  • curses.panel A panel stack extension for curses
  • cmd Support for line-oriented command interpreters
• Concurrent Execution
  • threading Thread-based parallelism
  • multiprocessing Process-based parallelism
  • multiprocessing.shared_memory Shared memory for direct access across processes
  • The concurrent package
  • concurrent.futures Launching parallel tasks
  • concurrent.interpreters Multiple interpreters in the same process
  • subprocess Subprocess management
  • sched Event scheduler
  • queue A synchronized queue class
  • contextvars Context Variables
  • _thread Low-level threading API
• Networking and Interprocess Communication
  • asyncio Asynchronous I/O
  • socket Low-level networking interface
  • ssl TLS/SSL wrapper for socket objects
  • select Waiting for I/O completion
  • selectors High-level I/O multiplexing
  • signal Set handlers for asynchronous events
  • mmap Memory-mapped file support
• Internet Data Handling
  • email An email and MIME handling package
  • json JSON encoder and decoder
  • mailbox Manipulate mailboxes in various formats
  • mimetypes Map filenames to MIME types
  • base64 Base16, Base32, Base64, Base85 Data Encodings
  • binascii Convert between binary and ASCII
  • quopri Encode and decode MIME quoted-printable data
• Structured Markup Processing Tools
  • html HyperText Markup Language support
  • html.parser Simple HTML and XHTML parser
  • html.entities Definitions of HTML general entities
  • XML Processing Modules
  • xml.etree.ElementTree The ElementTree XML API
  • xml.dom The Document Object Model API
  • xml.dom.minidom Minimal DOM implementation
  • xml.dom.pulldom Support for building partial DOM trees
  • xml.sax Support for SAX2 parsers
  • xml.sax.handler Base classes for SAX handlers
  • xml.sax.saxutils SAX Utilities
  • xml.sax.xmlreader Interface for XML parsers
  • xml.parsers.expat Fast XML parsing using Expat
• Internet Protocols and Support
  • webbrowser Convenient web-browser controller
  • wsgiref WSGI Utilities and Reference Implementation
  • urllib URL handling modules
  • urllib.request Extensible library for opening URLs
  • urllib.response Response classes used by urllib
  • urllib.parse Parse URLs into components
  • urllib.error Exception classes raised by urllib.request
  • urllib.robotparser Parser for robots.txt
  • http HTTP modules
  • http.client HTTP protocol client
  • ftplib FTP protocol client
  • poplib POP3 protocol client
  • imaplib IMAP4 protocol client
  • smtplib SMTP protocol client
  • uuid UUID objects according to RFC 9562
  • socketserver A framework for network servers
  • http.server HTTP servers
  • http.cookies HTTP state management
  • http.cookiejar Cookie handling for HTTP clients
  • xmlrpc XMLRPC server and client modules
  • xmlrpc.client XML-RPC client access
  • xmlrpc.server Basic XML-RPC servers
  • ipaddress IPv4/IPv6 manipulation library
• Multimedia Services
  • wave Read and write WAV files
  • colorsys Conversions between color systems
• Internationalization
  • gettext Multilingual internationalization services
  • locale Internationalization services
• Graphical user interfaces with Tk
  • tkinter Python interface to Tcl/Tk
  • tkinter.colorchooser Color choosing dialog
  • tkinter.font Tkinter font wrapper
  • Tkinter dialogs
  • tkinter.messagebox Tkinter message prompts
  • tkinter.scrolledtext Scrolled text widget
  • tkinter.dnd Drag and drop support
  • tkinter.ttk Tk themed widgets
  • IDLE Python editor and shell
  • turtle Turtle graphics
• Development Tools
  • typing Support for type hints
  • pydoc Documentation generator and online help system
  • Python Development Mode
  • doctest Test interactive Python examples
  • unittest Unit testing framework
  • unittest.mock mock object library
  • unittest.mock getting started
  • test Regression tests package for Python
  • test.support Utilities for the Python test suite
  • test.support.socket_helper Utilities for socket tests
  • test.support.script_helper Utilities for the Python execution tests
  • test.support.bytecode_helper Support tools for testing correct bytecode generation
  • test.support.threading_helper Utilities for threading tests
  • test.support.os_helper Utilities for os tests
  • test.support.import_helper Utilities for import tests
  • test.support.warnings_helper Utilities for warnings tests
• Debugging and Profiling
  • Audit events table
  • bdb Debugger framework
  • faulthandler Dump the Python traceback
  • pdb The Python Debugger
  • The Python Profilers
  • timeit Measure execution time of small code snippets
  • trace Trace or track Python statement execution
  • tracemalloc Trace memory allocations
• Software Packaging and Distribution
  • ensurepip Bootstrapping the pip installer
  • venv Creation of virtual environments
  • zipapp Manage executable Python zip archives
• Python Runtime Services
  • sys System-specific parameters and functions
  • sys.monitoring Execution event monitoring
  • sysconfig Provide access to Pythons configuration information
  • builtins Built-in objects
  • __main__ Top-level code environment
  • warnings Warning control
  • dataclasses Data Classes
  • contextlib Utilities for with-statement contexts
  • abc Abstract Base Classes
  • atexit Exit handlers
  • traceback Print or retrieve a stack traceback
  • __future__ Future statement definitions
  • gc Garbage Collector interface
  • inspect Inspect live objects
  • annotationlib Functionality for introspecting annotations
  • site Site-specific configuration hook
• Custom Python Interpreters
  • code Interpreter base classes
  • codeop Compile Python code
• Importing Modules
  • zipimport Import modules from Zip archives
  • pkgutil Package extension utility
  • modulefinder Find modules used by a script
  • runpy Locating and executing Python modules
  • importlib The implementation of import
  • importlib.resources Package resource reading, opening and access
  • importlib.resources.abc Abstract base classes for resources
  • importlib.metadata Accessing package metadata
  • The initialization of the sys.path module search path
• Python Language Services
  • ast Abstract syntax trees
  • symtable Access to the compilers symbol tables
  • token Constants used with Python parse trees
  • keyword Testing for Python keywords
  • tokenize Tokenizer for Python source
  • tabnanny Detection of ambiguous indentation
  • pyclbr Python module browser support
  • py_compile Compile Python source files
  • compileall Byte-compile Python libraries
  • dis Disassembler for Python bytecode
  • pickletools Tools for pickle developers
• MS Windows Specific Services
  • msvcrt Useful routines from the MS VC++ runtime
  • winreg Windows registry access
  • winsound Sound-playing interface for Windows
• Unix-specific services
  • shlex Simple lexical analysis
  • posix The most common POSIX system calls
  • pwd The password database
  • grp The group database
  • termios POSIX style tty control
  • tty Terminal control functions
  • pty Pseudo-terminal utilities
  • fcntl The fcntl and ioctl system calls
  • resource Resource usage information
  • syslog Unix syslog library routines
• Modules command-line interface (CLI)
• Superseded Modules
  • getopt C-style parser for command line options
• Removed Modules
• Security Considerations