---
id: crc
version: "7.1.0"
license: BSD-2-Clause
license_treatment: permissive
maintenance: aging
---

# crc — Pure Python CRC library

License: permissive · Maintenance: aging · Downloads: 911.0K/mo

## What it is and what it does

This is a pure Python library for computing CRC (cyclic redundancy check) checksums across multiple standard configurations and bit widths. It provides Calculator and Register classes to compute checksums on byte data, verify checksums against expected values, and supports both standard and table-based (optimized) computation modes.

The library ships with predefined configurations for common CRC variants (CCITT, XMODEM, MODBUS, GSM, PROFIBUS, and others across CRC8, CRC16, CRC32, and CRC64 widths), and allows defining custom configurations by specifying polynomial, init value, final XOR, and input/output reversal parameters. It has no external runtime dependencies and supports Python 3.8 through 3.12.

Use it for:

- Verify data integrity in serial communication protocols that use CRC error detection.
- Implement checksum validation for file transfers or network packet verification.
- Generate CRC values for embedded systems or legacy hardware that expect specific CRC configurations.
- Add data integrity checks to custom binary formats or wire protocols.
- Validate checksums in BZIP2, POSIX, or other standard formats that use CRC.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Calculate, verify, and manage CRC checksums using predefined configurations (CRC8, CRC16, CRC32, CRC64) or custom parameters.

Yes, for straightforward CRC checksum needs. The library is permissively licensed, has no dependencies, and covers common CRC configurations out of the box. Aging maintenance (647 days since last release) is a minor concern but the repository remains active and the codebase is stable; use it when you need standard CRC support without external dependencies.

## Install

pip install crc
uv add crc
poetry add crc

## Installing crc

Before you install: Low install friction with no runtime dependencies. Aging maintenance status (647 days since last release, last commit 2026-01-12) but repository remains active and not archived.

License in practice: BSD-2-Clause permissive license allows use in most projects with minimal restrictions; attribution required.

Quickstart:

pip install crc

from crc import Calculator, Crc8

calculator = Calculator(Crc8.CCITT)
checksum = calculator.checksum(bytes([0, 1, 2, 3, 4, 5]))
print(checksum)

Requires Python >= 3.8. Currently supports only bit widths that are full bytes (8, 16, 24, 32, etc.).

Verify before relying:

- Performance characteristics of optimized mode versus standard mode for large datasets.
- Whether the library handles streaming/incremental checksum updates efficiently.

## Package facts

- License: BSD-2-Clause (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: aging
- Downloads: 911.0K/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

crc checksum calculation, crc verification, cyclic redundancy check, crc8 crc16 crc32, checksum library python, data integrity verification, crc configuration, checksum, data-integrity, error-detection

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