---
id: unlzw3
version: "0.2.3"
license: unclear
license_treatment: permissive
maintenance: dormant
---

# unlzw3 — Pure Python decompression module for .Z files compressed using Unix compress utility

License: permissive · Maintenance: dormant · Downloads: 328.9K/mo

## What it is and what it does

unlzw3 is a pure Python decompressor for .Z files created by the Unix compress utility. It takes LZW-compressed binary data and returns a UTF-8 decoded string of the decompressed contents. Because it is written entirely in Python rather than wrapping compiled C code, it runs on any platform Python supports—including Windows—but at the cost of being slower than native utilities or CFFI-based alternatives.

The package has no runtime dependencies and installs with low friction. It is maintained sporadically (last release December 2024 after a 602-day gap), so it is suitable for stable, occasional use rather than active development. The implementation is based on Mark Adler's reference C code and has been modernized with testing and PyPI packaging.

Use it for:

- Decompress legacy .Z archives on Windows or macOS where native compress utilities are unavailable
- Read .Z-compressed data in a Python script without requiring system-level utilities or external C libraries
- Process archived datasets in .Z format as part of a data pipeline on any supported Python platform
- Integrate .Z decompression into a portable Python application without platform-specific build steps

## Worth the install?

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

Decompresses .Z files (Unix compress format) using pure Python, working cross-platform without compiled dependencies.

Yes, if you need to read .Z files and cannot rely on platform-specific tools or compiled alternatives. The pure Python implementation trades speed for portability and zero dependencies. No known security issues. Suitable for occasional use; dormant maintenance means no active development but also no churn.

## Install

pip install unlzw3
uv add unlzw3
poetry add unlzw3

## Installing unlzw3

Before you install: Low friction install with no runtime dependencies. Dormant maintenance (602 days since last release) but recent release on 2024-12-20 suggests occasional updates.

License in practice: MIT license (permissive) allows free use, modification, and distribution with minimal restrictions.

Quickstart:

import unlzw3
from pathlib import Path

uncompressed_data = unlzw3.unlzw(Path('file.Z').read_bytes())

Requires Python 3.9 or later

Verify before relying:

- Performance characteristics compared to platform-specific alternatives for large files
- Whether UTF-8 decoding assumption matches all real-world .Z file contents

## Package facts

- License: not declared (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: dormant
- Downloads: 328.9K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

.Z file decompression, unix compress decompressor, lzw decompression python, decompress .Z files, cross-platform z file reader, compression, cross-platform, legacy-format

[View on SkillFed](https://skillfed.io/packages/unlzw3) · [View on PyPI](https://pypi.org/project/unlzw3/)