---
id: bitarray
version: "3.10.1"
license: PSF-2.0
license_treatment: permissive
maintenance: active
---

# bitarray — efficient arrays of booleans -- C extension

License: permissive · Maintenance: active · Popularity: top 1,000 on PyPI

## Install

pip install bitarray
uv add bitarray
poetry add bitarray

## Description

bitarray: efficient arrays of booleans
======================================

This library provides an object type which efficiently represents an array
of booleans.  Bitarrays are sequence types and behave very much like usual
lists.  Eight bits are represented by one byte in a contiguous block of
memory.  The user can select between two representations: little-endian
and big-endian.  All functionality is implemented in C.
Methods for accessing the machine representation are provided, including the
ability to import and export buffers.  This allows creating bitarrays that
are mapped to other objects, including memory-mapped files.


Key features
------------

* The bit-endianness can be specified for each bitarray object, see below.
* Sequence methods: slicing (including slice assignment and deletion),
  operations ``+``, ``*``, ``+=``, ``*=``, the ``in`` operator, ``len()``
* Bitwise operations: ``~``, ``&``, ``|``, ``^``, ``<<``, ``>>`` (as well as
  their in-place versions ``&=``, ``|=``, ``^=``, ``<<=``, ``>>=``).
* Free-threading support (for GIL disabled CPython 3.14 and later)
* Fast methods for encoding and decoding variable bit length prefix codes.
* Bitarray objects...

## AI interpretation — verify before relying

bitarray provides an efficient, memory-compact array type for storing sequences of boolean values, with support for bitwise operations, slicing, and buffer protocol access—all implemented in C for performance.

Verdict: bitarray is a mature, actively maintained library (first released 2008-08-17, latest release 2026-08-07) with zero known vulnerabilities and broad platform coverage. Its C implementation and permissive PSF-2.0 license make it a reliable choice for performance-critical boolean array operations. Install friction is moderate but manageable given comprehensive wheel availability.

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