Add a Compress Quick Action to Finder

A Quick Action is a folder with a .workflow extension and two files in it. There is no database, no registry, no signing requirement. macOS looks for them in three places:

Inside one of them:

~/Library/Services/Compress Images.workflow/
└── Contents/
    ├── Info.plist        # the menu item and what file types it accepts
    └── document.wflow    # the actions, in order, with their parameters

Info.plist is the part that decides whether your action shows up at all. The four keys that matter, read straight out of a working bundle:

NSSendFileTypes is the one people get wrong. Set it to public.image and your action is invisible when a PDF is selected. Set it to public.item and it appears for everything, including folders, which is why your script needs to check what it was handed.

Open Automator (in Applications). Choose New Document, then Quick Action. At the top of the workflow pane set:

Search the action library for Run Shell Script and drag it in. Set Shell to /bin/zsh and, critically, set Pass input to as arguments. The default is to stdin, and with that default your file paths arrive on standard input where the script below will not see them. In the saved plist this is inputMethod: 1; Smol’s own Quick Action uses the same setting, which is a reasonable sanity check that it is the right one.

Paste this in. It is the exact script we ran.

#!/bin/zsh
# Compress each selected image into a sibling "Compressed" folder.
QUALITY=60
MAX_EDGE=2000

for f in "$@"; do
  [[ -f "$f" ]] || continue
  dir="${f:h}/Compressed"
  mkdir -p "$dir"
  base="${f:t:r}"
  out="$dir/${base}.jpg"
  n=2
  while [[ -e "$out" ]]; do out="$dir/${base} $n.jpg"; ((n++)); done

  if ! /usr/bin/sips -Z "$MAX_EDGE" -s format jpeg -s formatOptions "$QUALITY" \
       "$f" --out "$out" >/dev/null 2>&1; then
    continue
  fi
  # Never hand back a bigger file than we were given.
  if [[ $(/usr/bin/stat -f%z "$out") -ge $(/usr/bin/stat -f%z "$f") ]]; then
    /bin/rm -f "$out"
  fi
done

Save it with a name you want to see in the menu. Automator writes it to ~/Library/Services/ and it is live.

Four things in that script are load-bearing.

"$@" with the quotes, not $* or $(cat). A Finder selection can contain Screenshot 2026-09-26 at 14.02.11.png, and unquoted expansion turns that into five broken arguments.

Absolute paths to every binary. A Quick Action does not inherit your shell’s PATH. /usr/bin/sips and /usr/bin/stat always resolve; a bare magick or cwebp from Homebrew will not. This is the single most common reason a script that works in Terminal does nothing from the context menu.

Output into a subfolder, not in place. The collision loop appends 2, 3 and so on, so running the action twice never overwrites the first result.

The size guard. sips defaults to JPEG quality 75, so an already-compressed image can come back larger — we measured a 157,425-byte file growing to 229,775 on a plain re-encode. When we ran the finished Quick Action over two files, the 3.4 MB original produced a 289,061-byte result and the already-small 157,425-byte file produced nothing at all, because the guard deleted the worse output. That is the behavior you want and almost no tutorial includes it. The full list of sips quality behaviors is in the sips command reference.

You can run a saved workflow from the command line, which is how the numbers above were taken: automator -i /path/to/file.jpg MyAction.workflow. Note that man automator documents a single -i; a Finder multi-select passes the whole list, but from the shell you loop.

The gap between 0.16 s and 0.81 s is Automator’s harness starting up. It is a fixed cost per invocation, not per file, so it disappears the moment you select fifty images instead of one.

In order of how often it is the cause:

The Services database has not noticed. Force it:

/System/Library/CoreServices/pbs -flush

# Confirm it registered — you should see the bundle path
/System/Library/CoreServices/pbs -dump_pboard | grep "Compress Images"

That grep printed NSBundlePath = "/Users/…/Library/Services/Compress Images.workflow" for our test action, which is the definitive “yes, macOS can see it” check.

The file type does not match. If NSSendFileTypes is public.image and you selected a PDF, there is nothing wrong — the action is correctly hidden. Change it to public.item if you want one action for everything.

It is switched off. Open System Settings → Keyboard → Keyboard Shortcuts… → Services and look under Files and Folders. Every Quick Action on the machine is listed there with a checkbox, and an unchecked one never appears in a menu no matter how correct the plist is.

You are looking in the wrong submenu. Finder shows the first few Quick Actions inline on right-click and hides the rest behind Quick Actions → Customize…. With a dozen installed, yours may simply be below the fold.

Removal is deleting a folder. There is no uninstaller and nothing else to clean up.

# Remove one
rm -rf ~/Library/Services/"Compress Images.workflow"
/System/Library/CoreServices/pbs -flush

# See what you have
ls ~/Library/Services /Library/Services

If you want it out of the menu but not off the disk, uncheck it in System Settings → Keyboard → Keyboard Shortcuts… → Services instead. That pane is also where you assign a keyboard shortcut, which turns a right-click, hover, submenu, click into one keystroke.

To edit one, double-click the .workflow bundle and it opens in Automator. Changes take effect on save; no flush needed for an edit, only for an add or a delete.

One toggle in the app, and it installs the same kind of bundle in the same place. Ours is at ~/Library/Services/Compress with smol.workflow with CFBundleIdentifier: com.smol.quickaction, a menu item of Compress with smol, and NSSendFileTypes: ["public.item"] so it appears for images, PDFs, video and audio alike rather than only for photos.

It is one Run Shell Script action, exactly like the one you just built. The difference is what the script does: it reads ~/Library/Application Support/smol/settings.json at run time and uses whatever preset you last configured in the app, rather than hard-coding a quality number into the workflow. Change the app’s image quality and the Quick Action changes with it, with no Automator editing. It also prepends /Applications/Smol.app/Contents/Resources/binaries to PATH, so it reaches the bundled encoders instead of depending on Homebrew being installed.

Because Smol exposes its whole surface over an MCP server, an AI coding agent can check and change this without touching Finder at all. Asking one to report the state returned {"installed": true} on this machine, and install and uninstall are single tool calls. That matters less for a one-time setup than it does for reproducing a machine, which is the honest use case.

Almost always, if you can write twelve lines of shell. The script above is free, has no dependencies, works offline, survives OS upgrades, and you can read every line of it. If you want a right-click that resizes screenshots to 1,200 px before you paste them into a ticket, build it and never think about it again. We would rather you did that than paid us $29 for it.

Automator also wins when the recipe is yours. Strip metadata, then resize, then rename with a date prefix, then move to a dated folder, then post a webhook. No compression app is going to ship your exact pipeline. A shell script will run it.

Where a Quick Action gets thin:

Progress and cancellation. Select 400 photos and Automator gives you a small gear in the menu bar. There is no count, no per-file result, and Control-period leaves whatever sips was mid-write on disk.

Mixed file types in one selection. Handling images, PDFs, MP4s and WAVs in one script means four branches, four tools and four sets of quality flags. Doable, tedious, and easy to get subtly wrong.

Knowing what happened. A shell loop tells you nothing about which of your 400 files refused to shrink. You find out weeks later when one folder is still 2 GB.

Formats sips cannot write. WebP is readable but not writable, so a sips-based Quick Action cannot produce it at all.

That is the trade Smol’s one-time $29 buys: a queue with real progress, cancellation that leaves finished work finished, per-file results, mixed input types in a single drop, and AVIF and WebP as first-class outputs. If a right-click that runs sips covers your work, use the right-click.

For the batch-resize variant of this, including the destructive default in Automator’s own image actions, see batch resizing images with Automator. To skip the right-click entirely, a folder that compresses on drop is usually the better ergonomic. The PDF equivalent, with the Quartz filter and Ghostscript timings, is in batch compressing PDFs on a Mac. And if the images in question are going into a repository, a pre-commit hook catches them earlier than any Finder menu can.