OpenVDDK Offers an Apache-2.0 Stand-In for VMware's VDDK Library, Which VMware Restricted to Partners; Its Repository Takes No Pull Requests Yet
Cloud architect Andrija Panić published OpenVDDK, an Apache-2.0 library he calls a drop-in for VMware's VDDK; its README says the repository is read-only and pull requests are not accepted yet.
Overview
A cloud architect has published OpenVDDK, an open source library that The Register reports is an alternative to VMware’s Virtual Disk Development Kit (VDDK), which VMware recently withdrew from public downloads. According to the project’s README, it is provided under the Apache License 2.0, and its repository is “read-only for now: pull requests are not accepted yet.”
What VDDK Is and What VMware Said
VMware describes VDDK, as quoted by The Register, as “a set of libraries and utilities that enable software developers to create applications that can access and manipulate virtual disks.” The same report says users and VMware’s rivals also used it for migrating virtual machines to alternative virtualization platforms, and that “In August, VMware restricted access to VDDK downloads to its partners.”
In an earlier report, The Register quoted VMware as saying: “Access to the VDDK is still available through select TAP for its licensed use case, which has always been backup and recovery.” The Register explains that VMware calls third-party developers who work with its products technology alliance partners, or TAPs. A VMware spokesperson added: “The VDDK is not a customer entitlement. It is a software development kit covered by its own developer license and was never included with a Broadcom software purchase.”
The same Register report says Nutanix’s Move “requires a VDDK library to do the job” and that Red Hat “recommends using VDDK for migrations.”
What OpenVDDK Is
Andrija Panić told The Register he describes the project as “an independent drop-in for libvixDiskLib.so.8.0.3, the disk library that VMware backup and migration tools load to read virtual disks. It was written from scratch, using only public documentation and black-box testing, and contains no VMware code.” The Register adds that he wrote it in Go, with a thin C layer that exposes the same C interface, library name and symbol versions as VMware’s code, and that the tool can only read disks, not write them.
The README says programs written for VixDiskLib, “such as nbdkit’s VDDK plugin and virt-v2v,” load it in place of VMware’s library without source changes. It lists support for vSphere 6.7, 7.0 and 8.0, tested on 6.7 U3, 7.0.3 and 8.0.3, and 43 public functions of VixDiskLib 8.0.3. The Register quotes Panić as saying he also tested on vSphere 9.1.1, a version the README’s support list does not name.
Panić also told The Register that independent testers have reported successful use with Forklift, MTV on OpenShift, a Proxmox VE pipeline and custom nbdkit-based tools, and that he has received reports of production use. He stressed those reports are “not independently audited customer endorsements or a guarantee of suitability for every production environment.”
Licensing and Provenance Details
The repository’s LICENSE file carries the Apache License, Version 2.0 text, and the NOTICE file states: “Licensed under the Apache License, Version 2.0 (see LICENSE).” The README says every source file carries an SPDX-License-Identifier: Apache-2.0 line, that the project is provided on an “AS IS” basis, without warranties, under sections 7 and 8 of the licence, and that there is no guaranteed response time. The copyright line reads “Copyright 2026 Andrija Panić and the OpenVDDK contributors.”
The README says the library was written from public documentation, the facts any program needs to link against the library, and observation of what VMware’s library visibly does when it runs. Its PROVENANCE file says “No proprietary object code and no decompiler output is used,” and records VMware’s VDDK package as a reference input kept outside the repository. The README adds that anyone running differential tests against VMware’s library must obtain VMware’s VDDK package themselves.
Two process details appear in the repository. The README states that a library built from the published source has a different file hash from the 0.7.4 binary “distributed before the source was published,” and attributes the difference to a changed Go module path and the library recording its build commit. The PROVENANCE file also says that contributions “may be AI-assisted” and receive “the same tests, review, provenance and licensing checks as any other change.”
A Separate Project With the Same Name
A different repository, jimmyma-zhanwei/openvddk, also calls itself OpenVDDK. Its README describes it as a “clean-room, fully open-source (GPL-3.0) implementation of the VMware Virtual Disk Development Kit (VDDK).” The Register’s report does not mention it, and neither README states a relationship between the two projects.
Alternatives and Open Questions
The Register notes that OpenVDDK is not the only option: OpenNebula has a tool called OneSwap that it says has a 96 percent success rate, Nutanix tweaked Move so it can work without VDDK, and Red Hat is working on a fix and has provided a workaround.
The sources do not say whether VMware has commented on OpenVDDK, and they name only Panić as its author. The production use cited is Panić’s account as relayed by The Register, not an audited result.