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UltraISO logo.png
UltraISO screenshot.png
A screenshot of UltraISO
Developer(s)EZB Systems
Initial release20 April 2002; 19 years ago (2002-04-20)
Stable release / 30 July 2020; 8 months ago (2020-07-30)[1]
Operating systemMicrosoft Windows
PlatformIA-32 and x86-64
Available in40 languages
TypeOptical disc authoring software and virtual drive

UltraISO is an application for Microsoft Windows for creating, modifying and converting ISO image files used for optical disc authoring, currently being produced by EZB Systems.

Initially UltraISO was shareware however since 2006 it has turned 'Premium' and become chargeable.[2] The 'Free Trial' version is limited to ISO images of 300 MB or less.[3]


  • Duplicate CDs and DVDs to an ISO image.
  • Create ISO images from files located on a CD/DVD-ROM or hard disk.
  • Edit existing ISO files by adding, deleting, and creating files and folders.
  • Create compressed zisofs (.ISZ) images
  • Create bootable CD, DVD and floppy images.
  • Create a bootable USB flash or hard drive from a bootable disc image (works only with DOS, Windows NT and syslinux boot sectors). For this, the user can open an ISO image with UltraISO and choose 'Bootable' and 'Write disk image' to burn onto a bootable USB disk.
  • Converts: .BIN, .IMG, .CIF, .NRG, .BWI, .DAA, .DMG, .HFS and other formats to the standard ISO image.
  • Supports all ISO 9660 levels and the Joliet extension.
  • Optimization of ISO image file structures to save disc space.
  • Capable of mounting only ISOs to a virtual drive.
  • Create checksums for data verification of ISOs.
  • Multiple language support.
  • Built in digital audio player.
  • Supports UDF disc format and allows creation of bootable UDF disks.
  • Supports command line parameters[4]

ISZ format[edit]

UltraISO uses a proprietary format known as ISZ. The format is advertised as "ISO Zipped", even though it is not a simple zip archive. The format uses zlib or bzip2 to compress the data, and can support AES encryption of various strengths. The file format specification is available publicly on EZB Systems's website.[5] The format is now supported by third party applications such as Daemon Tools, Alcohol 120% and CDemu.

See also[edit]


  1. ^ "UltraISO Revision History".
  2. ^ (http://www.ezbsystems.com/ultraiso/order.htm)
  3. ^ http://www.softpedia.com/reviews/windows/UltraISO-Premium-Review-27870.shtml
  4. ^ http://www.ezbsystems.com/ultraiso/cmdline.htm
  5. ^ "ISZ File Format Specification". EZB Systems. 2006-07-03. Retrieved 2008-09-24.

External links[edit]