What is the OVA file format?
The .ova format is used to store data packages concerning a virtual machine in a single portable file. Specifically, .ova files bundle an .ovf XML descriptor with supporting files - a .mf manifest, an optional .cert signature, and virtual-disk images (.vmdk or .vhd) - packaged as an uncompressed TAR archive.
Data contained within .ova files cannot be run as unprocessed software. They must be imported and processed with specialised applications designed for running virtual machines. The .ovf descriptor is always placed first in the TAR, allowing a hypervisor to read the VM configuration before extracting the disk images.
Security & safety
RISK: MEDIUMAn OVA delivers a complete, bootable operating system someone else built - treat it like an executable, not a document. A malicious or backdoored appliance runs real software the moment you start it. Mitigations: download appliances only from the vendor or a trusted source, verify the .mf/.cert checksums when provided, keep the VM on an isolated/NAT network until you trust it, and don't share host folders or clipboard with an unknown guest. The OVA file itself won't infect the host just by sitting on disk, but importing and powering it on does run its code.
Format details
in a nutshellFULL NAMEOpen Virtualization Format Archive
DEVELOPERDMTF (Distributed Management Task Force); promoted by VMwaresince OVF 1.0 published by DMTF in 2009 (DSP0243); .ova single-file packaging followed
CATEGORYDisk Image Files
MIME TYPEapplication/x-virtualbox-ova
TYPETAR archive bundling an OVF descriptor + virtual disk(s) (binary container)
STANDARDOpen · royalty-free
Programs that open OVA files
Windows3 apps
7-Zip
Open-source Right-click > 7-Zip > Open archive to inspect or extract the OVF/VMDK without importing (an OVA is a TAR). 
Oracle VirtualBox
Open-source File > Import Appliance, select the .ova, review/adjust CPU-RAM-disk, then Import.
VMware Workstation Pro
Free File > Open, pick the .ova, choose a name/location; free for personal use since 2024 (Broadcom). Register a free Broadcom account to download. 
macOS2 apps
Oracle VirtualBox
Open-source File > Import Appliance, select the .ova, Import. Apple-silicon Macs need the VirtualBox ARM build and an ARM guest. 
Linux3 apps
VMware OVF Tool
Free Command line: ovftool source.ova target.vmx - convert/validate OVA to VMware runtime format. Now hosted on developer.broadcom.com.
GNOME Boxes / virt-manager (QEMU/KVM)
Open-source Extract the .vmdk from the OVA (tar -xf), convert with qemu-img to qcow2, then create a VM around it. Technical details
deep spec| Container format | Uncompressed POSIX TAR archive (512-byte block records) |
| File signature | `ustar` ASCII string at byte offset 257; no signature at byte 0 |
| MIME type | `application/x-virtualbox-ova` |
| First archive member | The `.ovf` XML descriptor must appear first in the TAR, enabling streaming import before full extraction |
| OVF descriptor | XML file conforming to the DMTF OVF schema (DSP8023); declares virtual hardware, disk references, networks and properties |
| Manifest file | `.mf` file inside the archive lists SHA-1 or SHA-256 checksums for each packaged component |
| Signature file | Optional `.cert` file carries an X.509 certificate and signed digest for appliance authenticity verification |
| Supported virtual-disk formats | `.vmdk` (VMware), `.vhd` / `.vhdx` (Microsoft), `.vdi` (VirtualBox) |
| Compression | None at the OVA level; contained `.vmdk` images may use internal stream compression (zlib/deflate) |
| Multi-file counterpart | An `.ovf` package distributes the same files separately; `.ova` wraps them into one portable bundle |
| Command-line export (VMware) | `ovftool source.vmx output.ova` |
| Command-line import (VirtualBox) | `VBoxManage import appliance.ova` |
| TAR inspection | Any TAR utility (e.g., `tar -tf appliance.ova`) can list or extract internal files without a hypervisor |
| Hypervisor support | VMware ESXi, Workstation and Fusion; Oracle VirtualBox; QEMU/KVM via virt-manager; Microsoft Hyper-V with conversion |
| Released | OVF 1.0 published by DMTF in 2009 (DSP0243); .ova single-file packaging followed |
| Open standard | Yes · royalty-free |
| Specification | www.dmtf.org |
OVA conversions
Possible
.OVA .VHDGUIDE
Yes - extract the disk from the OVA, then convert it to VHD using VirtualBox or qemu-img.
How to convert
.OVA .OVFGUIDE
Yes, OVA converts to OVF without any data loss - the fastest method is extracting the archive with 7-Zip (or…
How to convert
.OVA .VMDKGUIDE
Yes, getting a VMDK from an OVA is straightforward - the disk is already inside the archive and 7-Zip (free)…
How to convert
.OVA .VDIGUIDE
Yes - import the OVA into VirtualBox and it stores the disk as VDI, or use one VBoxManage command on the…
How to convert
Community Q&A
asked by usersNo questions yet - be the first to ask about OVA files.
Frequently asked questions
How do I open an OVA file?
You import it into a hypervisor, not a viewer. In VirtualBox use File > Import Appliance; in VMware Workstation/Fusion use File > Open/Import. Both then create a runnable VM from it.
Is VirtualBox or VMware free for opening OVA?
Both. VirtualBox is open-source and free; VMware Workstation Pro and Fusion Pro became free for personal use in 2024 after Broadcom's acquisition (free Broadcom account required to download).
How do I extract the VMDK disk from an OVA?
An OVA is a TAR archive - rename it to .tar or open it with 7-Zip and pull out the .vmdk (and the .ovf). No special tools needed.
Can I import a VMware OVA into VirtualBox?
Usually yes - OVF/OVA is a cross-vendor standard. If the import complains about hardware sections, retry with the 'relax OVF validation' / 'continue anyway' option, or convert with VMware's ovftool first.
What's the difference between OVA and OVF?
Same standard, different packaging. OVF is a folder of files (XML descriptor + separate disks); OVA bundles them into a single TAR file for easier transfer.
Why won't my OVA import?
Common causes: a checksum mismatch from an incomplete download, a hardware section the target hypervisor rejects (use 'ignore/relax validation'), or not enough free disk space for the expanded virtual disks.
References
1Oracle VirtualBox - Importing and Exporting Appliancesdocs.oracle.com
2DMTF - Open Virtualization Format (OVF) standardwww.dmtf.org
