Guard Plugins

NOTE: Guard maintainers are not responsible for the quality or suitability of the plugins below. (Though, some plugins are maintained by Guard core developers.)

Ordering is generally by popularity/user-friendliness/completeness/support/active-development. Disputes about order should be resolved by project "star" count.

NOTE: if any plugins are broken or outdated, try the following:

1. find the gem on rubygems.org, then go to the homepage
2. file an issue there and wait up to a few days for the author to respond
3. if the plugin author isn't responding CC a Guard maintainer in the issue (e.g. me: @e2)

NOTE: some plugin authors work on their own forks instead of the forks in the Guard organization. Please update the links below if they point to the wrong/outdated fork.

Popular / Featured / Well supported

Plugin	When to use
guard-bundler	installs/updates gems when Gemfile changes
guard-rspec	Smart/incremental RSpec runner
guard-minitest	runs Minitest and Test/Unit tests
guard-cucumber	Reruns changed/affected Cucumber Features
guard-zeus	Zeus speeds up startup time for Rails commands (development, server, testing)
guard-jasmine	Frontend testing using PhantomJS/Webkit
guard-jekyll-plus	Extensive plugin for working with Jekyll projects
guard-brakeman	Scans your Rails application for known security holes (CVE's)
guard-rubocop	Check your source files to style violations and potential problems
guard-puppet	Helps build Puppet catalogs for deploying and managing sites and servers
guard-shell	Runs shell commands when changes happen - also supports notifications and long -running programs
guard-livereload	Reloads browser whenever web pages change
guard-nanoc	rebuild Nanoc websites
guard-process	Manages background processes (servers, daemons)
guard-yield	runs any Ruby code (without the need to write a Guard plugin)
guard-kjell	runs command once when watched file changes

Rails related

Plugin	When to use
guard-brakeman	Scans your Rails application for known security holes (CVE's)
guard-migrate	Migrates the database whenever you add/change migrations
guard-jammit	Compressing assets (JS, CSS)
guard-annotate	Inserts "cheatsheets" about your database schema into your source files
guard-passenger	Manages the Passenger server (restarts when necessary)
guard-sprockets	Recompiles assets using Sprockets
guard-llsprockets	recompiles assets using Sprockets
guard-cogs	guard-sprockets alternative
guard-rails_best_practices	check if code matches Rails Best Practices
guard-bower_rails	Automatically install/update Rails bower dependencies
guard-bundler-audit	check for gems with vulnerabilities
guard-consistency_fail	detect missing unique indexes in Rails projects
guard-flow	runs flow type checker on Rails javascript files
guard-railsbp	Rails Best Practices runner

Website generating/authoring

Plugin	When to use
guard-jekyll-plus	Extensive plugin for working with Jekyll projects
guard-middleman	Rebuilds Middleman static websites
guard-nanoc	rebuild Nanoc websites
guard-mouch	Mouch/CouchDB apps
guard-sculpin	Sculping site generator (PHP)
guard-staticmatic	Staticmatic site generator

Web CSS/template processing/compiling

Plugin	When to use
guard-coffeescript	Compiles CoffeeScript files
guard-compass	Rebuilds your CSS files in Compass Sass projects
guard-tilt	?
guard-sass	Recompiles Sass files to CSS
guard-slim	regenerate slim templates
guard-haml	compile Haml templates to HTML
guard-less	compile LESS templates
guard-stylus	compile Node.js Stylus CSS templates
guard-erb	compiles erb files
guard-haml-coffee	compiles HamlCoffe templates to JavaScript
guard-herbalizer	converts Haml to Erb using herbalizer
guard-hogan	compiles hogan mustache templates
guard-jade	compile Jade files
guard-lessc	compiles less file to a target output file using lessc
guard-mthaml	compile Haml to PHP, Twig or static HTML
guard-mustachejs	compile mustachejs into a single js file

General Web Development

Plugin	When to use
guard-livereload	Reloads browser whenever web pages change
guard-embertools	rebuilds application.js when ember files are modified
guard-pusher	Send messages to multiple iPad/iPhone browsers (like "reload page")
guard-shopify	automatically upload and update Shopify templates when they change
guard-shopifytheme	update through Shopify theme
guard-premailer	inline CSS in email templates
guard-sprite-factory	Web Development
guard-i18n-js	export i18n js translations

Restarting servers/daemons/workers

Plugin	When to use
guard-process	Manages background processes (servers, daemons)
guard-redis	restarts Redis server when needed
guard-go	Run and restart go programs and servers when changed
guard-resque	restarts Resque workers
guard-resque-scheduler	restarts Resque in dev mode
guard-delayed	automatically restarts delayed_job workers
guard-webrick	Restarts WEBrick server when needed
guard-rack	restarts Rack app server
guard-puma	restarts Puma app server
guard-foreman	reruns foreman
guard-goliath	restarts Goliath apps
guard-grunt	restarts Grunt
guard-gulp	restarts Gulp
guard-pow	restarts Pow applications
guard-rails	manage Rails server (handling Zeus parameters, daemon mode, etc.)
guard-restarter	restarts some process
guard-shotgun	restart Sinatra server
guard-sidekiq	restart Sidekiq workers
guard-spin	restart Spin server
guard-unicorn	restart Unicorn server

Web asset optimization

Plugin	When to use
guard-uglify	compress JavaScript files using uglifier gem
guard-steering	Speed up Handlebar.js templates by precompiling them
guard-concat	concat assets (JS/CSS) into single files
guard-image_optim	optimizes images with image_optim
guard-imageoptim	optimze images with ImageOptim-CLI
guard-sprockets2	sprockets for Rails, Sinatra or Rack

Testing (Ruby)

Plugin	When to use
guard-cucumber	Reruns changed/affected Cucumber Features
guard-rspec	Smart/incremental RSpec runner
guard-minitest	runs Minitest and Test/Unit tests
guard-motion	reruns specs for RubyMotion (iOS, Android, OSX Ruby apps)
guard-bdd	run tests in order: unit tests, integration tests, then acceptance tests
guard-combustion	testing Rails Engines
guard-spinach	BDD framework on top of Gherkin
guard-spinoff	preload your Ruby environment using fork()
guard-spork	manage Spork DRb servers

Testing (JRuby workarounds)

Plugin	When to use
guard-jruby-minitest	no-startup-code JRuby Minitest test reloader
guard-jruby-rspec	keeps a JVM warmed up for your specs
guard-rspec-jruby	improve JRuby test performance

Testing (Various)

Plugin	When to use
guard-prove	reruns Perl tests
guard-jenkins	sets a Jenkins status image depending whether there's a failure or not
guard-cunit	run CUnit tests
guard-elixir	runs Elixir tests using "mix test"
guard-gotest	runs Go tests
guard-haskell	runs Haskell specs
guard-julia	runs Julia tests
guard-pytest	runs pytest (Python)
guard-rackunit	runs Racket's RackUnit tests
guard-rebar	use Rebar to run Erlang tests
guard-roxy	runs Roxy unit tests (MarkLogic apps)
guard-sclang	runs SuperCollider unit tests
guard-busted	runs busted (Lua)

Testing (JavaScript)

Plugin	When to use
guard-jasmine	Frontend testing using PhantomJS/Webkit
guard-teaspoon	Web testing with PhantomJS or Selenium WebDriver
guard-jaspec	run Jaspec JavaScript files
guard-konacha	runs Konacha (mocha + chai) JavaScript tests on Rails apps
guard-karma	runs the Karma JS test runner
guard-jessie	Jasmine runner using Node.js Jessie runner
guard-jasmine-node	reruns Jasmine Node.js tests
guard-jasmine-headless-webkit	rerun Jasmine tests in a headless WebKit instance
guard-mocha-node	test node.js code with mocha
guard-phantomjs-jasmine	run jasmine specs with PhantomJS

Testing (Java)

Plugin	When to use
guard-maven	run Maven tests (Java)
guard-gradle	builds and runs Java tests (Gradle projects)
guard-gradle-android-test	runs Java Gradle tests for Android
guard-java	run tests in Java (using Ant or shell) + Android support

Testing (PHP)

Plugin	When to use
guard-phpunit	Guard::PHPUnit automatically runs your tests
guard-codeception	run Codeception tests (PHP)
guard-phpspec	runs PHPSpec

Testing (iOS)

Plugin	When to use
guard-xcodebuild	run xcodebuild tests
guard-xctool-test	run xctool test command on save
guard-frank	rerun Frank-Cucumber (iOS) features
guard-calabash-ios	return Calabash iOS Cucumber features
guard-cedar	runs Cedar (Objective-C) BDD tests
guard-ocunit	run OCUnit tests on ios-sim

Code Quality

Plugin	When to use
guard-cane	fails the build if your source files fail the quality level
guard-rubocop	Check your source files to style violations and potential problems
guard-haml-lint	Check your HAML-specific style and lint checks
guard-slim-lint	Check your Slim-specific style and lint checks
guard-flog	creates flog reports
guard-reek	find code smells
guard-rubybeautify	beautifies Ruby code
guard-rubycritic	detects code smells in Ruby using Rubycritic
guard-srb	Typechecks Ruby code with Sorbet

Code Quality (Javascript)

Plugin	When to use
guard-jshint-node	detect errors and potential problems in JavaScript files
guard-coffeelint	run coffeelint
guard-jshint-on-rails	uses jshint on Rails project
guard-jslint	runs jslint on JavaScript files

Code Quality (PHP)

Plugin	When to use
guard-phpcs	detects and fixes PHP, JS and CSS violations
guard-phpmd	runs PHP Mess Detector on changed files

Documentation

Plugin	When to use
guard-hologram	generates beautiful style guides for CSS
guard-docbook-status	update docbook document overviews (structure stats)
guard-readme-on-github	preview GitHub pages locally before pushing them to GH
guard-rocco	regenerates Rocco docs
guard-gimli	convert markup files (markdown, rdoc) into PDF files
guard-git-scribe	rebuild git-scribe ebooks
guard-markdown	convert Markdown files to HTML
guard-ronn	compile man pages
guard-inch	documentation measurement tool for Ruby
guard-rdoc	rebuild rdoc on code changes
guard-redcarpet	use Redcarpet gem to process markdown to html
guard-yard	rebuild documentation with Yard

DevOps / Chef

Plugin	When to use
guard-foodcritic	lint tool for Opscode Chef cookbooks
guard-chef	watches and reloads Chef recipes automatically
guard-kitchen	use Kitchen to develop Chef cookbooks
guard-knife	update Chef cookbooks, data bags, envs and roles automatically
guard-librarian	automatically install Chef cookbook dependencies in Cheffile using librarian-chef
guard-rake-vagrant	converge cookbooks and run integration tests
guard-rsync	automatically sync directories with RSync whenever they change
guard-remote-sync	RSync runner

DevOps / Puppet

Plugin	When to use
guard-puppet	Helps build Puppet catalogs for deploying and managing sites and servers
guard-puppet-lint	runs puppet-lint

Deploying / DevOps / System services

Plugin	When to use
guard-s3	Synchronize folders with Amazon S3 buckets
guard-flopbox	synchronize directories via SFTP
guard-autoupload	upload files using SFTP or FTP
guard-bosh	update Cloud Foundry BOSH config (large scale distributed services)
guard-clockwork	restart Clockwork instances (Clockwork = Cron replacement written)
guard-fig	help develop docker containers using fig
guard-shoryuken	Amazon AWS SQS thread based message processor

Editor helpers (ctags generators)

Plugin	When to use
guard-ctags-bundler	regenerates CTags files so editors can find method definitions
guard-ctags-composer	for PHP projects

Utility

Plugin	When to use
guard-bundler	installs/updates gems when Gemfile changes
guard-shell	Runs shell commands when changes happen - also supports notifications and long -running programs
guard-yield	runs any Ruby code (without the need to write a Guard plugin)
guard-rake	reruns a rake task when files change
guard-post	automatically load text files into database records (Mongoid, ActiveRecord, etc.)
guard-lilypond	Engraving music scores
guard-zen	Runs Ruby Koans
guard-blogger	update Blogger templates
guard-cocoapods	installs CocoaPods
guard-bundler	installs/updates gems when Gemfile changes
guard-copy	copy files whenever files are created or modified
guard-copy3	copies files and folders whenever files are created or modified
guard-entangle	expands files inline
guard-gitpusher	automatically uploads changed files to Git repository
guard-mirror	copies CoffeeScript/Styles/Jade source into another location
guard-npm	instal/update npm packages from package.json
guard-pushover	send Pushover real-time notifications to mobile devices
guard-ragel	generate Ragel state machine files

Guard Plugin development

Plugin	When to use
guard-compat	Essential for developing and testing Guard Plugins
guard-yield	runs any Ruby code (without the need to write a Guard plugin)
guard-helpers	helpers modules for Guard plugins

Not yet categorized/described

NOTE: I (@e2) haven't gone through these - please move these into the above categories if any are usable/useful enough:

Plugin	When to use
guard-addremove	?
[guard-asciidoctor]:	?
[guard-bacon]:	?
guard-blink1	?
[guard-bower]:	?
guard-catalog	?
[guard-cloudformation]:	?
guard-concatfilter	?
guard-cop:	?
[guard-cucumber-js]:	?
guard-depend	?
guard-ecukes	?
[guard-ejs]:	?
guard-erlang	?
guard-evergreen	?
guard-faye	?
[guard-fixture_builder]:	?
[guard-flay]:	?
[guard-go]:	?
[guard-haml-ext]:	?
[guard-haml2erb]:	?
guard-handlebars	?
[guard-i18next]:	?
[guard-jasmine-rails]:	?
guard-jenkins	?
guard-jet	?
[guard-jetty]:	?
[guard-js-static-require]:	?
[guard-jshintrb]:	?
[guard-jslint-on-rails]:	?
[guard-jslint-on-rails-for-1.1.1]:	?
[guard-jst]:	?
[guard-koans]:	?
guard-konacha-rails	?
guard-konacha-version	?
guard-live-set	?
[guard-lono]:	?
guard-markdown	?
guard-markdown2impress	?
guard-minitest-decisiv	?
guard-notifier-blink1	?
[guard-notifier-git_auto_commit]:	?
guard-notifier-gntp_only-darwin	?
[guard-opal-rails]:	?
guard-openscad	?
guard-parallel_all	?
guard-pdflatex	?
[guard-phpunit2]:	?
guard-play	?
guard-predictionio	?
[guard-preek]:	?
[guard-preserves]:	?
guard-processing	?
[guard-prostores]:	?
[guard-python-unittest]:	?
[guard-rackup]:	?
[guard-rna]:	?
guard-rrails	?
guard-rubby	?
[guard-ruby]:	?
[guard-rust]:	?
guard-schema	?
guard-schema	?
guard-seeds	?
[guard-shellexec]:	?
[guard-simple_shell]:	?
guard-sporkminitest	?
guard-sprite-factory	?
guard-steering	?
[guard-stitch]:	?
guard-stitch-plus	?
guard-strainer	?
guard-sublime-ctags	?
guard-sunspot	?
[guard-sync]:	?
guard-tap	?
guard-tay	?
guard-teabag	?
[guard-templates]:	?
guard-templates-jshaml	?
guard-test	?
guard-tishadow	?
guard-titan	?
guard-toc	?
guard-treetop	?
guard-typescript	?
guard-unity	?
guard-vows	?
guard-webhook-notifier	?
guard-webpack	?
guard-xcode	?
guard-xcoder	?
guard-yaml	?
guard-yamlsort	?
[guard-yardstick]:	?
guard-yeti	?
guard-zeus-client	?
[guard-zeus_server]:	?

Outdated/Obsolete plugins

Outdated Plugin	Why outdated/obsolete
Rails-Autotester	probably replaced with Guard::Minitest
guard-autorefresh	superseeded by Guard::LiveReload
guard-coffeedripper	probably outdated
guard-db	probably replaced with guard-migrate
guard-ego	Guard can now reload itself
guard-focus	probably can be replaces with Guard::RSpec with custom config
guard-hydra	probably replaced with Guard::RSpec using parallel specs (check Guard::RSpec Readme)
guard-jekyll	superseeded by guard-jekyll-plus
guard-jessie	likely superseeded by guard-jasmine
guard-jslint-on-rails	probably outdated
guard-jstd	probably superseeded by other JavaScript testing Guard plugins
guard-krl	updates cloud-based Kinetic Rules Engine rule files (company dissolved)
guard-mozrepl	probably superseeded by Guard::LiveReload
guard-phantomjs	probably superseeded by other JavaScript testing Guard plugins
guard-rails-assets	not sure if it works with Rails 4
guard-rspectacle	Embedded RSpec runner - probably better to use Guard::Rspec or Guard::Zeus
guard-soca	likely outdated
guard-spring	guard-rspec supports running RSpec with Spring and a lot more
guard-stendhal	likely outdated
guard-stitch	alternative to guard-sprockets, but may be outdated
[guard-jekyll2]	probably replaced with guard-jekyll-plus
guard-fast_spec	probably obsolete
guard-railstestdb	replaced with guard-migrate
guard-reloader	obsolete?