Mount disk images as writable disks with OSFMount


OSFMount from Passmark Software is a free disk image mounting software with some nice features that distinguish it from similar programs; specifically, OSFMount can mount image files as WRITABLE disks, and also allows to create virtual drives in memory.

Mounting means using a file as a virtual disk in My Computer. There are several utilities that can write the whole contents of a CD, DVD or hard disk to create a disk image file (with file extension ISO, IMG, NRG, DD etc). With disk mounting software like OSFMount You can then assign the image file to a drive letter and use it as a virtual disk drive.

This is useful in many instances; for example is netbooks without an optical drive, where you can download the image of an original installation CD/DVD, mount the image and install the program from the mounted image. Another example is creating backup images of Your hard-disk and with the help of disk mounting software You can access single files from the image without the need to restore the whole disk.

Reading vs. Writing: many disk mounting software can only create read-only disks but OSFMount allows creation of writable drives. This means You can take an image file, make it appear as a drive, change the files and folders inside and then save the modified image file.

RAM drives: another useful feature of OSFMount is creating drives in memory (RAM drives). If you have lot of memory there are benefits to be had to making a very fast virtual drive in memory, which can speed up working with applications considerably. An example would be creating a RAM drive for Photoshop temporary files.

Typically all the contents of a RAM drive are lost after shutting down the computer but OSFMount allows for writing e the contents of the RAM drive to a disk image file for mounting next time You need the files.

Note that after creating a new empty RAM drive you have to format it to desired file system (e g NTFS); if you want to keep the contents of the drive you need to select ‘Save to image file’.

OSFmount screen2OSFmount screen1

On exiting OSFMount the virtual drives remain available as they are created uses Windows virtual disk drivers. For dismounting the drives you can run OSFMount again and save/dismount the drives.


  • Most disk images can be mounted as writable.
  • Supports a wide range of disk image files (IMG, DD, ISO, Nero NRG, WMWare VMDK etc); many of which it can mount as writable. The following are NOT writeable: ISO, BIN, and VMWare Image (VMDK).
  • Create virtual disks in RAM and write the contents to image file afterwards.


  • No windows integration: i.e. no entries in the context menu when right-clicking on an image file, unlike many of the other programs in it’s category.
  • OSFMount virtual CD/DVD is not sufficient for some games that require installation media (use Virtual Clonedrive, Daemon Tools etc instead because they use different virtual disk drivers).

The verdict: a great program if you want to work with your images as writable disks, or if you need to work with RAM images, or if you simply want a reliable image mounting software with some very interesting functionality (note that it will not mount ISO, BIN, and VMWare VMDK image format as writable but will mount IMG, DD, and a host of others as such).

It’s only real drawback it the lack of right click integration in Windows explorer, which is not an insignificant disadvantage in terms of the user experience.

For other, similar programs previously mentioned on Freewaregenius: WinCDEmu, MagicDisk, Pismo file mount

Compatibility: Windows XP, Vista & Win 7, Windows Server 2000, 2003, 2008. Both 32bit and 64bit versions available.

OSFMount is available in the OSFMount homepage.