Build your installer media.
Bootabler downloads macOS installers from Apple, then turns them into bootable USB drives, disk images and virtual machine disks. This guide walks through every feature.
Create a bootable USBRead the FAQGet Bootabler1. Get an installer
Open the macOS Downloader and download a version, or use Add macOS Installer to pick an installer app you already have. Installers found in Applications and Downloads appear in the sidebar automatically.
2. Choose what to make
Select an installer, then choose Create Bootable USB, Create Disk Image or one of the options in the More menu.
3. Pick the target
For a USB, select the drive in the disk list. For an image, the format and folder come from Settings.
4. You stay in control
Nothing is erased until you confirm. You can cancel at any time, and Bootabler stops the work immediately.
macOS Downloader
Download full macOS installers straight from Apple's catalogs.
Catalog
Choose the Catalog to browse (for example public or developer catalogs). Turn on Show All Versions and Show older macOS versions to see everything Apple still publishes.
Compatibility check
Each version is checked against your Mac. Versions your Mac can't run are marked Not compatible with this Mac, with the reason shown.
Release notes
The Release Notes button next to a version shows Apple's notes for it.
Copy link / Download As…
Copy the download URL, or save the package to a location of your choice with Download As….
Integrity check
Downloads are verified against Apple's published checksums. A damaged download is reported so you can retry it.
New version alerts
Bootabler watches Apple's catalog and notifies you when a new macOS version appears. Turn this off with Notify me when a new macOS version appears in Settings.
- Open the macOS Downloader from the sidebar.
- Pick a catalog and find the version you want.
- Click download. Progress, speed and time remaining appear on the row.
- When it finishes, Bootabler can install the package for you (see below).
Download Queue & Packages
Download several versions without saturating your connection.
Simultaneous downloads
Choose how many downloads run at once (1–5) in Settings › Downloads. Extra downloads wait in a queue and start automatically.
Reorder the queue
Use Move to the front of the queue or Start downloading now on a waiting row.
Retry
A failed download can be retried with Retry, and your download list is saved when you quit the app.
After installing a package
Once the InstallAssistant.pkg has been installed, Bootabler can Ask each time, Keep it or Move it to the Trash.
Auto-install
Automatically install macOS when download finishes installs the package as soon as it is complete.
Installer Library
See every installer on your Mac in one place.
What it shows
Each installer's name, version, size and location, with a badge when it is not compatible with this Mac.
Check integrity
Verify an installer's signature and contents without creating any media.
Duplicates
Duplicate copies are flagged, and Remove Duplicate Copies moves the extras to the Trash.
Housekeeping
Show an installer in Finder, or move it to the Trash, directly from the list.
- Choose File › Installer Library… (⇧⌘L).
- Review the list and use the buttons on each row.
Installer Folders
Tell Bootabler where else your installers live.
Default places
Applications and Downloads are always searched.
Add your own
Click Add Folder… in the sidebar, or use File › Add Installer Folder…. Subfolders up to two levels deep are searched. Your folders are remembered between launches.
Grouped by folder
The sidebar and the multi-installer picker group installers by the folder they are in, so you can tell copies apart.
Remove a folder
Manage the list in Settings › Downloads › Installer Folders.
Bootable USB
Turn a USB drive into a macOS installer.
Select the drive
External drives are listed with name, size and format. Enable Show internal disks as install targets in Settings if you need internal disks listed.
Several drives at once
Select more than one drive to write the same installer to all of them in a single run.
Erase or keep free space
When the drive already has other volumes, Bootabler asks whether to Erase the whole drive or Keep Free Space as Untitled and use only the unused space. Choosing the second option leaves your existing volumes untouched.
Automatic formatting
Automatically format USB drives before writing prepares the drive for you. A drive that is too small is rejected before anything is erased.
After writing
Choose to Automatically safely eject USB upon completion. The result is checked afterwards (see Verification).
- Select an installer in the sidebar.
- Select the USB drive in the disk list.
- Click Create Bootable USB (⇧⌘U).
- Confirm. Watch the progress, and the Advanced Verbose Log if you want the details.
Multi-Installer USB
Put several macOS versions on one drive.
Pick installers by folder
Installers are listed under the folder they came from, so duplicates in different places are easy to tell apart.
Accurate sizing
Bootabler measures each installer, adds the space the installer tool needs, and shows a layout summary: space used by installers and what remains. If the selection won't fit, you're told before anything starts.
Untitled volume
Space left over becomes a volume named Untitled after the last installer is written, so the drive is still useful for files.
Whole drive or free space only
If the drive already holds your volumes, choose to use only its free space. Existing volumes are kept.
One notification
One completion notification is sent when the whole job is done, not one per installer.
- Select the target USB drive.
- Open the More menu and choose Create Multi-Installer USB….
- Tick the installers to include and review the layout summary.
- Choose whole drive or free space only, then confirm.
Disk Images
Save an installer as a single image file.
Formats
ISO (.iso), CDR (.cdr) and compressed DMG (.dmg). Virtual machine disk formats are covered in the next section.
Where it is saved
Choose a default folder in Settings › Disks & Images, or turn on Ask where to save each image to choose each time. The default is your Desktop.
Checksum file
A SHA-256 checksum can be written alongside the image so you can confirm a copy later.
Disk space check
Bootabler checks that your disk has room for the working copies before it starts.
- Choose a format in Settings › Disks & Images.
- Select an installer.
- Click Create Disk Image (⇧⌘I). The button shows the format you chose.
Virtual Machine Disks
Create installer disks for VMware, VirtualBox, Parallels, Hyper-V and QEMU.
| Format | Use it with | Written by |
|---|---|---|
| VMDK | VMware Fusion, Workstation, ESXi; VirtualBox | Bootabler (or compact file with qemu-img) |
| VDI | VirtualBox | Bootabler (or expanding file with qemu-img) |
| VHD | Hyper-V, Virtual PC, VirtualBox, Parallels | Bootabler |
| VHDX | Hyper-V 2012 and later | qemu-img required |
| QCOW2 | QEMU, UTM | qemu-img required |
| Raw disk (.img) | QEMU, UTM, dd | Bootabler |
Built to boot
VM hard disks start through the VM's EFI firmware, which needs a GUID (GPT) partition map. Bootabler builds these images that way, writes the installer onto them, then wraps the result in the format you chose.
Checked before wrapping
With verification on, the bootable structure is checked on the raw disk before it is converted.
Boot hints
Settings shows how to attach each format, and the finished task repeats the steps. For example VirtualBox needs Enable EFI and the ICH9 chipset, and Hyper-V needs a Generation 2 machine.
Parallels
Parallels' own .hdd format is proprietary. Use ISO or DMG to install directly, or attach a VMDK or VHD.
qemu-img. Install it with brew install qemu. Bootabler warns you in Settings and refuses to start if it is missing.Write Image to USB
Copy an existing disk image onto a drive.
Supported images
Choose an image file (for example an ISO or DMG you made earlier) and a target drive.
Confirmation
You confirm the target before the drive is erased.
- Select the target USB drive.
- Open More (or the File menu) and choose Write Disk Image to USB….
- Choose the image and confirm.
Verification
Know the media you made is good.
| Level | What it does |
|---|---|
| Off | No checks after writing. |
| Quick | Checks the structure and boot files. This is the default. |
| Full | Also reads back and checksums the installer image. |
Set the level in Settings › Disks & Images › Verification. Before a job starts, Bootabler also checks the installer itself and tells you if it is damaged or has an expired certificate.
Progress & Cancel
See what is happening, and stop it when you need to.
Progress view
Appears as soon as a task starts and shows the current step, percentage and elapsed time. Several tasks can run at once and are listed under Active Tasks.
Advanced Verbose Log
Shows timestamped steps from the very first one, including disk preparation, so a slow step is easy to spot.
Cancel
Click Cancel and confirm. Bootabler stops the installer tool immediately, including the part that runs with administrator rights.
Busy disks
A drive in use by a running task is marked as busy and can't be chosen again. It becomes available as soon as the task ends.
Notifications & Menu Bar
Leave a long job running and come back when it's done.
Completion notifications
Turn on Notify me when a task finishes to be alerted about finished USB, image, download and install tasks. They show even while Bootabler is in front.
Menu bar progress
Show progress in the menu bar displays running tasks and their progress at the top of your screen.
Notification permission
If notifications don't appear, use Open Notification Settings… in Settings › General.
History
A record of what Bootabler has done.
What's recorded
Each finished or failed task with its type, target, time and result.
Open it
Choose File › History… (⌘Y).
Export or clear
Use Export… to save the list, or Clear History to remove it.
Expired Certificates
Older installers can fail because Apple's certificate inside them has expired.
Automatic detection
If a job fails in a way that looks like an expired installer certificate, Bootabler says so and shows How to fix….
Guided fix
The help sheet explains the cause and gives the steps to work around it.
Settings
Open with ⌘,. Settings has three tabs.
| Tab | What it controls |
|---|---|
| General | Notifications, Keychain (saved administrator password), update checks (daily, weekly, monthly or never) and appearance. |
| Disks & Images | Internal-disk targets, auto-format, auto-eject, image format, save location, ask each time, verification level and menu bar progress. |
| Downloads | Default download location, simultaneous downloads, installer folders, after-install package action, auto-install and new-version alerts. |
Shortcuts
| Shortcut | Action |
|---|---|
| ⌘S | Scan for Installers |
| ⌘R | Refresh Disk List |
| ⌘O | Add macOS Installer |
| ⇧⌘U | Create Bootable USB |
| ⇧⌘I | Create Disk Image |
| ⇧⌘L | Installer Library |
| ⌘Y | History |
| ⌘U | Check for Updates |
| ⌘, | Settings |
Accessibility
Bootabler works with VoiceOver and keyboard navigation.
Labelled controls
Buttons, progress bars and download rows have descriptive labels, such as "Download progress for…" and "Check integrity of…".
Keyboard
Every command above has a menu item, and most have a shortcut.
Frequently Asked Questions
Got questions? We've got answers.
Which macOS versions can I make installers for?
Any full installer Apple still publishes, plus installers you already have. Older versions appear when Show older macOS versions is on.
Why does Bootabler ask for my password?
The installer tool needs administrator rights to write to a drive. If you choose to save the password it is kept in your macOS Keychain; you can remove it in Settings › General.
Will it erase my whole drive?
Only if you choose Erase. For a USB drive or multi-installer job with existing volumes, choose the free-space option to keep them.
Can I make a drive with several macOS versions?
Yes, with Multi-Installer USB. See that section for how sizing works.
The drive is too small.
Bootabler checks the size before erasing. Use a larger drive, or for multi-installer jobs select fewer installers.
Why can't I choose VHDX or QCOW2?
These need qemu-img. Install it with brew install qemu and try again.
My virtual machine won't boot the image.
Check the boot hint for the format in Settings. The VM must use EFI firmware, and Hyper-V needs a Generation 2 machine. Parallels should install from the ISO or DMG.
A task seems stuck.
Open the Advanced Verbose Log. Each step is timestamped, so you can see which one is taking time. You can cancel at any point.
My installer fails with a certificate error.
Choose How to fix… in the error message to see the steps.
Which macOS versions can run Bootabler?
macOS 11 Big Sur and later.