Google CRC32C

1.8.0 verified Tue May 12 auth: no python install: stale quickstart: stale

A Python wrapper of the C library 'Google CRC32C', currently at version 1.8.0. It supports Python versions from 3.9 onwards and is actively maintained with regular updates.

pip install google-crc32c

Common errors

error ModuleNotFoundError: No module named 'google_crc32c' ↓

cause The `google-crc32c` package, though installed with a hyphen, is imported in Python code using an underscore (`google_crc32c`). This error occurs if the package is not installed or if Python cannot find it in the current environment.

fix

Ensure the package is installed using pip install google-crc32c and that your Python environment is correctly configured.

error ERROR: Could not build wheels for google-crc32c which use PEP 517 and cannot be installed directly ↓

cause This error typically occurs during installation when pre-compiled wheels for your specific Python version and operating system/architecture are not available, requiring the package to be built from source. It indicates missing C build tools and development headers necessary to compile the underlying C library.

fix

Install the necessary build dependencies for your system, such as python3-dev (or python-dev), gcc, and build-essential on Linux (e.g., sudo apt-get install python3-dev gcc build-essential). For Windows, ensure you have a compatible C++ build environment, like the one provided by Visual Studio.

error As the c extension couldn't be imported, `google-crc32c` is using a pure python implementation that is significantly slower. ↓

cause This is a `RuntimeWarning` indicating that the optimized C extension of the `google-crc32c` library failed to load, leading to a fallback to a slower pure Python implementation. This usually happens due to issues during the package's compilation or if the compiled extension cannot be found/loaded at runtime.

fix

Ensure that your system has the required C build tools and Python development headers installed (as described in the 'Could not build wheels' fix) and then try reinstalling google-crc32c.

error ImportError: cannot import name 'crc32c' from 'google_crc32c' ↓

cause Users might incorrectly try to import a top-level `crc32c` function directly from the `google_crc32c` module. The `google-crc32c` library exposes its core functionality through `value` and `extend` functions, not a single `crc32c` function directly at the module level.

fix

Import the specific functions provided by the library, for example: from google_crc32c import value or from google_crc32c import extend to calculate CRC32C checksums.

Warnings

breaking Python versions below 3.9 are not supported. ↓

fix Upgrade Python to 3.9 or higher.

breaking The 'crc32c' object cannot be imported from 'google_crc32c', even with the correct import syntax 'from google_crc32c import crc32c'. This typically occurs when the library's C extension fails to build or load, preventing the `crc32c` function from being properly exposed by the module. A pure Python fallback might be used, but could also lead to issues if not correctly initialized. ↓

fix Ensure your build environment contains necessary C compiler tools (e.g., 'build-base' on Alpine, 'gcc' on Debian/Ubuntu) and Python development headers (e.g., 'python3-dev' or 'python-dev'). Install these dependencies before installing `google-crc32c`. For Alpine, this often means `apk add build-base python3-dev`. If a pure Python fallback is intended, verify its implementation correctly exposes `crc32c`.

Install compatibility stale last tested: 2026-05-12

python os / libc status wheel install import disk

3.10 alpine (musl) - - - -

3.10 slim (glibc) - - - -

3.11 alpine (musl) - - - -

3.11 slim (glibc) - - - -

3.12 alpine (musl) - - - -

3.12 slim (glibc) - - - -

3.13 alpine (musl) - - - -

3.13 slim (glibc) - - - -

3.9 alpine (musl) - - - -

3.9 slim (glibc) - - - -

Imports

crc32c
```
from google_crc32c import crc32c
```
Ensure to import from 'google_crc32c' namespace.

Quickstart stale last tested: 2026-04-23

Calculate the CRC32C checksum of a byte string.

import os
from google_crc32c import crc32c

# Example usage
data = b'This is a test'
checksum = crc32c(data)
print('CRC32C Checksum:', checksum)