pywatchman

What it is and what it does

pywatchman is a Python client library for interacting with Watchman, Meta's file watching service. It provides a programmatic interface to monitor filesystem changes across Windows, macOS, and Linux. The package itself has no runtime dependencies and is maintained by Meta's source control team.

Watchman watches files and records when they change, then can trigger actions like rebuilding assets in response. The Python client lets developers integrate file-watching capabilities into build systems, development tools, and automation scripts. It supports modern Python versions and is marked as production-stable.

Use it for:

• Integrate file watching into build systems to trigger asset rebuilds when source files change
• Monitor project directories in development tools to detect when to re-run tests or linters
• Watch for filesystem changes in automation scripts that need to react to file modifications
• Build file-change-triggered workflows in IDEs or editor plugins via the Watchman service

Worth the install?

AI-flagged interpretation of the facts on this page — verify before relying

pywatchman is a Python client for Watchman, a file watching service that monitors filesystem changes and can trigger actions when matching files change.

Yes, if you need file-watching capabilities and are willing to manage the Watchman daemon separately. The client itself is stable, permissively licensed, actively maintained, and has no dependency overhead. Verify that Watchman is available on your target platform and that you understand the daemon-vs-client architecture before committing.

Install

pywatchman on PyPI

pip install pywatchman

uv add pywatchman

poetry add pywatchman

Installing pywatchman

Before you install

Medium install friction due to platform-specific wheels (macOS arm64 binaries provided); no runtime dependencies. Active maintenance with recent release 63 days ago and ongoing repository activity.

License in practice

Permissive BSD-style license (with portions under MIT from the 'six' project) allows commercial and private use with attribution; no copyleft restrictions.

Quickstart

pip install pywatchman

import pywatchman

client = pywatchman.client()
result = client.query('watch-project', '/path/to/watch')

Requires Watchman daemon to be installed and running on the system; pywatchman is only the client library.

Verify before relying

• Whether Watchman daemon must be installed separately on the system for pywatchman to function
• Supported platforms beyond the macOS arm64 wheels shown in friction evidence
• Whether this is a pure Python client or requires compiled components on other platforms

Package facts

Evidence: pywatchman-4.0.0-cp310-cp310-macosx_11_0_arm64.whl; pywatchman-4.0.0-cp311-cp311-macosx_11_0_arm64.whl; pywatchman-4.0.0-cp312-cp312-macosx_11_0_arm64.whl; pywatchman-4.0.0-cp313-cp313-macosx_11_0_arm64.whl; pywatchman-4.0.0-cp314-cp314-macosx_11_0_arm64.whl; pywatchman-4.0.0-cp38-cp38-macosx_11_0_arm64.whl; pywatchman-4.0.0-cp39-cp39-macosx_11_0_arm64.whl

Keywords: watchman, inotify, fsevents, kevent, kqueue, portfs, filesystem, watcher

Tags

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