macos-iso-builder

# Overview

Build bootable macOS installer ISOs and DMGs directly from Apple's servers — no Mac required.

This project has two parts:
1. A script (`mkmaciso`) that uses only macOS built-in tools and commands to download and install the full macOS installer from Apple's servers into **/Applications**, and then creates bootable ISO/DMG images.
2. GitHub Action workflows that run `mkmaciso` on Azure datacenter-hosted Mac minis if you don't have macOS.

## Before you start

Check [Release page](https://github.com/LongQT-sea/mkmaciso/releases/latest) first - someone might've already built what you need. If not, see [How to use](#how-to-use) to build your own.

> [!Important]
> GitHub-hosted runners are a free public resource — please use them responsibly.

## Disk Image Formats

| | ISO | DMG |
|---|---|---|
| Best for | Virtual Machines | Bootable USB |
| VM Support | Attach as virtual DVD | Attach as virtual hard disk |
| Layout | Hybrid UDF/HFS | Raw GPT disk image |

**ISO files** - These work great for VMs *(Proxmox, QEMU, VMware)*. Just attach them like a virtual DVD. They'll even mount in Windows if you need to poke around inside.

**DMG files** - Flash these to a USB drive with [Rufus](https://rufus.ie/en/#download) *(Windows)*, `dd` *(Linux)*, or `asr` *(macOS)* to make bootable installation media. For VM use, convert them to `.vhd` *(for Hyper-V)* or `.vmdk` *(for VMware)* with `qemu-img`. QEMU/Proxmox can use the raw disk image without conversion.
> Note: DMG files ship with a `.img` suffix *(e.g. macOS_Sequoia.dmg.img)* so Rufus can find them without switching to "All files" in Explorer.

## Supported versions

Pretty much everything from OS X Lion (10.7, 2011) through the latest macOS Tahoe (26, 2025). Full list:

Lion, Mountain Lion, Mavericks, Yosemite, El Capitan, Sierra, High Sierra, Mojave, Catalina, Big Sur, Monterey, Ventura, Sonoma, Sequoia, Tahoe.

---

## How to use

### Don't have macOS? Use GitHub Actions

> [!TIP]
> <details>
> <summary>Click here to watch a visual guide (GIF)</summary>
>
> ![How to fork and run workflow](https://raw.githubusercontent.com/LongQT-sea/macos-iso-builder/main/.github/how_to_fork_and_run_workflow.gif)
>
> </details>

1. Star and then [Fork](https://github.com/LongQT-sea/macos-iso-builder/fork) this repository (requires a GitHub account).<br>
   <img src="https://raw.githubusercontent.com/LongQT-sea/macos-iso-builder/main/.github/star_and_fork.jpg" width="500">
2. Navigate to the **Actions** tab in your forked repository.
3. Click the green **"I understand my workflows, go ahead and enable them"** button.
4. Select a workflow from the left sidebar:
   * **Recovery ISO** *(recommended)* - Small recovery image, builds in 2-5 minutes. Good for VMs.
   * **Full Installer** - Complete offline installer, 5-18GB, takes 5-60 minutes to build.
5. Click the **"Run workflow"** button and configure the workflow inputs:

   * **macOS version** – Choose a version (*Sequoia*, *Sonoma*, etc.).
   * **Image format