Compositor على الماك: بديل فوتوشوب المجاني وكيف يعدّل Claude Code تصميمكCompositor on Mac: the free Photoshop alternative, and how Claude Code edits your design

Key terms

Compositor

A free, open source image editor for Mac. Layers, masks and Photoshop's full set of blend modes in the same order, with the same shortcuts.

.comp file

A Compositor project. A folder of PNG layer images plus one manifest.json that describes the layers.

manifest.json

The file that tells Compositor the layer order, opacity, blend mode and position of every layer.

Agent

An AI that can read and write files on your computer by itself, like Claude Code.

The steps

1. 1

   Step 1

   Check that your Mac runs it

   Compositor runs only on Apple Silicon Macs, M1 through M5, with macOS 26 or later.

   Open the Apple menu, then About This Mac, and check the chip and the macOS version first.

   support.apple.com

   

   Tip: Intel Macs will not run it.

2. 2

   Step 2

   Install the app

   Two ways. Download it from robbietilton.com/compositor or from the GitHub Releases page.

   Or, with Homebrew, paste this into Terminal.

   robbietilton.com

   

   PromptInstall command (Terminal)

   Copy

   brew install --cask robbietilton-compositor

3. 3

   Step 3

   Open one of your PSD files

   Drag any PSD onto the app. It opens Photoshop PSD and PSB files in 8 bit RGB, plus JPEG, PNG, HEIC, TIFF, SVG and RAW.

   CMYK files will not open, so convert them to RGB first.

   Tip: The shortcuts match Photoshop, and you can remap them in Settings.

4. 4

   Step 4

   Save your project as a .comp

   Save the canvas as a project, for example demo.comp on your Desktop, and keep it open.

   That file is really a folder: the layer images plus a manifest.json. That is why any agent can edit the design with no plugin and no API.

   

5. 5

   Step 5

   Let Claude Code design it

   Open Claude Code in Terminal and paste the prompt below.

   Compositor 1.3 or later reloads the canvas every time the agent writes the files, usually within half a second, so you watch the layers build up.

   

   PromptPrompt for Claude Code

   Copy

   Read docs/writing-comp-files.md in github.com/robbietilton/Compositor, then design [describe your design, e.g. a moody night poster for my café] in [~/Desktop/demo.comp]. Work in steps, one or two layers at a time. Keep the documentID as it is, write the PNGs first, then write the manifest to a temp file and rename it over manifest.json.

   Tip: If the canvas does not change, an image name probably does not match its layer id, or a blend mode is misspelled.

6. 6

   Step 6

   Take over by hand

   What you get are ordinary layers. Select one, change its opacity or blend mode, paint on its mask, save.

   If you have unsaved changes, Compositor asks before it replaces them with the agent's version, so your work is never lost.

   PromptEdit prompt

   Copy

   In [~/Desktop/demo.comp], keep every existing layer. Add a Curves adjustment layer on top that gives a [warm / cool] grade, set the [layer name] layer to [Multiply] at [70]% opacity, then tell me what you changed.

Ready prompts to copy

Look at [path to reference image]. In [~/Desktop/demo.comp], rebuild its layout as separate layers: background, main subject, title text area, and a soft shadow. Name every layer clearly and use only these blend modes: Normal, Multiply, Screen, Overlay.

Duplicate [~/Desktop/demo.comp] into three projects sized 1080x1350, 1080x1920 and 1920x1080. Re-place every layer so nothing important is cropped, and keep the layer names the same.