What is the VMX file format?
.vmx is a plain-text file that stores configuration data for VMware, a virtual machine management software (now part of Broadcom). Each line follows a key = "value" format describing the virtual machine's hardware and settings.
.vmx files store various virtual machine-related data, including:
- display and video card support
- number of CPU cores available to the VM
- memory size
- network card settings
- disk and storage device paths (pointing to .vmdk virtual disk files)
- access to USB, CD/DVD and other hardware devices
Virtual machines can be sorted into groups, with extended group details stored in a .vmxf file; when a virtual machine is added to a group, an entry is added to the related .vmx file. Originally, Linux VMware Workstation used .cfg files instead of .vmx files. Hand-editing a .vmx is a common way to apply settings the GUI does not expose.
Security & safety
RISK: LOWA .vmx is a small plain-text config and is not executable on its own, so the file itself is low risk. Two practical cautions: (1) a maliciously edited .vmx could point a VM at unexpected devices/host paths or weaken isolation, so only run .vmx files from VMs you trust, and review suspicious 'key = value' lines (host folder sharing, device passthrough) before powering on; (2) the risk really lives in the VM's DISK (.vmdk) - booting an untrusted VM runs someone else's OS, so keep unknown VMs on an isolated network.
Format details
in a nutshellFULL NAMEVMware Virtual Machine Configuration Fileaka VMware VM config, VMX configuration file
DEVELOPERVMware (now part of Broadcom)since 1999 (VMware Workstation 1.0; the .vmx config has been the VM definition ever since)
CATEGORYSettings Files
MIME TYPEapplication/x-vmware-vmx
TYPEPlain-text virtual-machine configuration - 'key = value' property list
Programs that open VMX files
Windows2 apps
VMware Workstation Pro
Free File > Open, select the .vmx (or double-click) to load and power on the VM. Free for personal use since 2024.
Any text editor (Notepad++ / VS Code)
Open-source Open the .vmx as text to view or hand-edit 'key = value' settings (close the VM in VMware first). 
macOS2 apps
VMware Fusion
Free File > Open, choose the .vmx (inside the .vmwarevm bundle) to run the VM. Free for personal use since 2024. 
Linux2 apps
Any text editor
Open-source Open the .vmx in a text editor (nano/gedit/vim) to view or edit the configuration. Technical details
deep spec| Format type | Plain-text `key = "value"` property list; one directive per line, no sections or nesting |
| MIME type | `application/x-vmware-vmx` (also accepted as `text/plain`) |
| Character encoding | UTF-8; declared by a `.encoding = "UTF-8"` line that conventionally appears first in the file |
| Config format version | `config.version` key (value `"8"` since Workstation 4) distinguishes file-format revisions from hardware compatibility versions |
| Hardware compatibility level | `virtualHW.version` key increments with each VMware product generation (e.g., `"21"` in Workstation Pro 17 / ESXi 8.0) |
| Typical file size | 1-10 KB; a simple VM has a few dozen lines, a complex one several hundred |
| File identification | No binary magic bytes; identified by characteristic opening keys such as `config.version = "8"` and `.encoding = "UTF-8"` |
| Encryption | Optional; when VM Encryption is enabled the `.vmx` is encrypted at rest and gains `encryption.keyId` and `encryption.keySafe` keys |
| Referenced companion files | `.vmdk` (virtual disk image), `.vmsd` (snapshot descriptor), `.vmsn` (memory snapshot), `.nvram` (firmware/BIOS state) |
| Supported platforms | Windows and Linux (VMware Workstation Pro), macOS (VMware Fusion), VMware ESXi hypervisor datastores |
| VM settings categories | CPU count and topology, RAM allocation, display/GPU, disk controllers, network adapters, USB, optical drives, guest OS type, boot order |
| Developer | VMware, Inc. - acquired by Broadcom in November 2023; format maintained under Broadcom's VMware division |
| Historical predecessor | Early Linux VMware Workstation releases used `.cfg` files in the same role before `.vmx` became standard |
| Hand-editing examples | Common tweaks include `disk.EnableUUID = "TRUE"`, `cpuid.coresPerSocket`, and `isolation.tools.copy.disable = "FALSE"` |
| Released | 1999 (VMware Workstation 1.0; the .vmx config has been the VM definition ever since) |
| Latest version | Tracks the virtualHW.version / hardware compatibility level (e.g. hw v21 in Workstation 17) |
| Specification | knowledge.broadcom.com |
VMX conversions
Possible
.VMX .TXTGUIDE
A VMX file is already plain text, so opening it in any text editor and saving as .txt is all that is needed.
How to convert
.VMX .OVFGUIDE
Yes, a VMware VM can be exported to OVF -- the fastest way is one ovftool command: ovftool vm.vmx vm.ovf.
How to convert
.VMX .OVAGUIDE
Yes - use VMware OVF Tool (ovftool) with one command to package the whole VM into a single OVA file.
How to convert
.VMX .PVMGUIDE
Yes - import the VMware VM into Parallels Desktop on Mac; it reads the .vmx and .vmdk files and produces a…
How to convert
.VMX .PVSGUIDE
Yes - open Parallels Desktop on your Mac and use File > Import to bring in the VMware VM folder; Parallels…
How to convert
Not possible
Community Q&A
asked by usersNo questions yet - be the first to ask about VMX files.
Frequently asked questions
How do I open a .vmx file?
Open it in VMware Workstation (Windows/Linux) or VMware Fusion (Mac) - File > Open or double-click - to load and start the VM. Both are now free for personal use. To just read it, open it in any text editor.
Is VMware free for opening .vmx files?
Yes - VMware Workstation Pro and Fusion became free for personal use in 2024 (broadly free under Broadcom in 2025). You no longer need a paid licence to open a .vmx.
Can I open a VMware .vmx in VirtualBox?
Not directly - VirtualBox doesn't read .vmx. Either export the VM to OVF/OVA with ovftool and import that, or create a new VM in VirtualBox and attach the existing .vmdk disk.
What's the difference between .vmx and .vmdk?
The .vmx is the VM's settings (CPU, RAM, devices); the .vmdk is the virtual hard disk holding the OS and data. The .vmx points to the .vmdk.
Can I edit a .vmx file by hand?
Yes - it's plain text. Close the VM in VMware first, then edit the 'key = value' lines in a text editor (e.g. to change RAM or enable nested virtualization). Keep a backup.
My VM won't open - is the .vmx broken?
Possibly. Check that the disk paths (scsi0:0.fileName) point to existing .vmdk files, that virtualHW.version isn't newer than your VMware build, and restore the .vmx from backup or recreate the VM around the existing .vmdk if needed.
References
1Broadcom Knowledge - VMware virtual machine files (.vmx and others)knowledge.broadcom.com
2Broadcom - VMware Workstation/Fusion now free for personal useblogs.vmware.com
