# facebook/watchman

Watches files and records, or triggers actions, when they change.

Repository: https://github.com/facebook/watchman
Canonical: https://ross.abutalabs.com/products/watchman
Homepage: https://facebook.github.io/watchman/
Language: C++
License: MIT
License Family: permissive
Last push: 2026-08-26T16:35:40+00:00

## Health v2 (maintenance only)
Score: 95/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 99, release rhythm 87, longevity 100
- inputs: {"age_days": 5025, "days_push": 7, "days_rel": 9, "gap_med": 7.0, "n_releases_24m": 101}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 13694, forks 1064 (observed 2026-08-28T04:11:04.610276+00:00)

## What it is
Watchman is a file watching service that recursively monitors directory trees and records when files change. It can trigger actions, such as rebuilding assets, when matching files change.

## Use cases
- watch a source directory for file changes
- trigger a build or minification when css files change
- query which files changed since the last check
- subscribe to file change events in a directory tree
- speed up incremental builds in large repositories

## When to choose
- you need efficient recursive file watching across windows, macos, and linux
- you want to run commands automatically when matching files change
- you need a long-running service with clients in python, rust, or javascript

## When to avoid
- you only need simple one-off file polling in a script
- you need to follow symlinked directories, which watchman does not do
- you want a lightweight in-process file watcher rather than a background service

## Facets
- artifact type: service
- maturity: stable
- function: file-system, developer-tools, cli
- domain: developer-tools
- platform: windows, cross-platform, cli
- tags: file-watching, file-monitoring, build-triggers, facebook, command-line, automation, linux, macos

## Member repositories
- facebook/watchman (main) score 95

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:04.610276+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:13:06.766257+00:00, confidence not recorded.
  - readme: https://github.com/facebook/watchman (fetched 2026-08-28T04:11:04.610276+00:00, sha 3254e4120b74)
  - homepage: https://facebook.github.io/watchman/ (fetched 2026-08-29T08:07:28.806769+00:00, sha 9a872c15b28b)
- Data as of 2026-08-30T08:39:29.467469+00:00.