diff --git a/README.md b/README.md
index 2028924f..6d7a6388 100644
--- a/README.md
+++ b/README.md
@@ -66,7 +66,7 @@ Supported languages
 * **R** ([*styler*](https://github.com/r-lib/styler))
 * **Reason** ([*bsrefmt*](https://github.com/glennsl/bs-refmt))
 * **ReScript** ([*rescript format*](https://www.npmjs.com/package/rescript))
-* **Ruby** ([*rufo*](https://github.com/ruby-formatter/rufo))
+* **Ruby** ([*rubocop*](https://github.com/rubocop/rubocop), [*rufo*](https://github.com/ruby-formatter/rufo), [*standardrb*](https://github.com/testdouble/standard))
 * **Rust** ([*rustfmt*](https://github.com/rust-lang-nursery/rustfmt))
 * **Scala** ([*scalafmt*](https://github.com/scalameta/scalafmt))
 * **Shell script** ([*beautysh*](https://github.com/lovesegfault/beautysh), [*shfmt*](https://github.com/mvdan/sh))
diff --git a/format-all.el b/format-all.el
index db783e72..7db9b7fd 100644
--- a/format-all.el
+++ b/format-all.el
@@ -66,8 +66,9 @@
 ;; - Python (black, yapf)
 ;; - R (styler)
 ;; - Reason (bsrefmt)
+;; - ReScript (resfmt)
 ;; - ReScript (rescript)
-;; - Ruby (rufo)
+;; - Ruby (rubocop, rufo, standardrb)
 ;; - Rust (rustfmt)
 ;; - Scala (scalafmt)
 ;; - Shell script (beautysh, shfmt)
@@ -479,6 +480,40 @@ If ARGS are given, those are arguments to EXECUTABLE.  They don't
 need to be shell-quoted."
   (apply 'format-all--buffer-hard nil nil nil executable args))
 
+(defun format-all--ruby-gem-bundled-p (gem-name)
+  "Internal helper function to check if GEM-NAME is listed in the current project's Gemfile.lock."
+  (let* ((lockfile "Gemfile.lock")
+         (dir (locate-dominating-file (buffer-file-name) lockfile)))
+    (and dir
+         (with-temp-buffer
+           (insert-file-contents (expand-file-name lockfile dir))
+           (re-search-forward (format "^    %s " (regexp-quote gem-name)) nil t))
+         t)))
+
+(defun format-all--buffer-hard-ruby
+    (gem-name ok-statuses error-regexp root-files executable &rest args)
+  "Internal helper function to implement ruby based formatters.
+
+GEM-NAME is the name of a Ruby gem required to run EXECUTABLE.
+
+For OK-STATUSES, ERROR-REGEXP, ROOT-FILES, EXECUTABLE and ARGS, see `format-all--buffer-hard'."
+  (let* ((error-regexp
+          (apply #'regexp-or
+                 "Bundler::GemNotFound"
+                 (concat "bundler: failed to load command: "
+                         (regexp-quote executable))
+                 (concat (regexp-or "bundle" (regexp-quote executable))
+                         ": command not found")
+                 (if error-regexp (list error-regexp))))
+         (command-args
+          (append (if (format-all--ruby-gem-bundled-p gem-name)
+                      '("bundle" "exec"))
+                  (cons executable (format-all--flatten-once args)))))
+    (format-all--buffer-hard
+     ok-statuses error-regexp root-files
+     (car command-args)
+     (cdr command-args))))
+
 (defvar format-all--executable-table (make-hash-table)
   "Internal table of formatter executable names for format-all.")
 
@@ -891,12 +926,26 @@ Consult the existing formatters for examples of BODY."
   (:install "gem install rufo")
   (:languages "Ruby")
   (:format
-   (format-all--buffer-easy
-    executable
+   (format-all--buffer-hard-ruby
+    "rufo" nil nil nil
+    "rufo"
     "--simple-exit"
     (when (buffer-file-name)
       (list "--filename" (buffer-file-name))))))
 
+(define-format-all-formatter rubocop
+  (:executable "rubocop")
+  (:install "gem install rubocop:'>=1.4.0'")
+  (:languages "Ruby")
+  (:format
+   (format-all--buffer-hard-ruby
+    "rubocop" '(0 1) nil nil
+    "rubocop"
+    "--auto-correct"
+    "--format" "quiet"
+    "--stderr"
+    "--stdin" (or (buffer-file-name) (buffer-name)))))
+
 (define-format-all-formatter rustfmt
   (:executable "rustfmt")
   (:install "rustup component add rustfmt")
@@ -964,6 +1013,17 @@ Consult the existing formatters for examples of BODY."
     '(0 1) ".*?:.*?:[0-9]+:[0-9]+: Parsing error:" nil
     executable "--fix" "--stdin")))
 
+(define-format-all-formatter standardrb
+  (:executable "standardrb")
+  (:install "gem install standard:'>=0.13.0'")
+  (:languages "Ruby")
+  (:format
+   (format-all--buffer-hard-ruby
+    "standard" '(0 1) nil nil
+    "standardrb"
+    "--fix"
+    "--stdin" (or (buffer-file-name) (buffer-name)))))
+
 (define-format-all-formatter styler
   (:executable "Rscript")
   (:install "Rscript -e \"install.packages('styler')\"")