Our Windows GUI for PBS is now merged upstream at tizbac

What the merge brought upstream

Tiziano did not just take the interface: he kept developing it in his repository. Based on the upstream main branch history as of 7 September 2026, here is what was added compared with our version:

• Reworked whole-machine backup (disk mode): progress across the whole job, real cancellation, VSS enforced.
• Rewritten documentation, with the README translated into a dozen languages.
• Branding chosen at build time: the executable and installer (WiX) branding is configurable. The code is shared, the brand is not — exactly the split described below.
• Bare-metal restore: tooling to build a WinPE rescue ISO and a Clonezilla ISO that can read a backup from the PBS.
• On Linux, a block-level snapshot engine (elastio-snap) for whole-machine backups.
• Packages for Debian, Arch (PKGBUILD) and Fedora (RPM spec) for the Go client. Not to be confused with our unofficial repository, which redistributes Proxmox's official client, written in Rust.
• A Docker build for the Windows GUI, to compile it from Linux.

How the two repositories fit together

• tizbac/proxmoxbackupclient_go is the reference project: the command-line client, the machine backup tools, and now the GUI, under a generic brand.
• rdemsystems/NimbusBackupClient is our distribution under the Nimbus Backup brand: MSI installer, Windows service, file-driven deployment and a VirusTotal report published for every version. We port the upstream changes into it: 0.4.1 (9 October 2026) is built on the upstream main branch at commit 3c1b989 of 9 October, which no upstream release contains yet, and brings in, among other things, the client-side encryption developed by Tiziano.
• Mind the configuration. The two versions do not store their configuration file in the same place: switching straight from Nimbus Backup to a build of the upstream repository does not pick up your existing configuration. The intended path is to go through Nimbus Backup 0.4.0 first, released on 24 September 2026: it merges the upstream code back in, aligns its configuration folders with upstream's and copies your files there if needed. We will then propose an upstream change so that this copy also happens on a direct upgrade, without going through 0.4.0.
• Windows binary signing: ours are signed since 0.4.1 (Authenticode, through Azure Artifact Signing, certificate issued to RDEM SYSTEMS); 0.4.0 had shipped unsigned, as opening the account was blocked on Microsoft's side. As of 9 October 2026, the latest upstream release (v1.1.3) carries no Authenticode signature. SHA-256 hashes and VirusTotal reports are still published (see the antivirus false positive page).

The rest of this article tells how it all started, at the end of July.

What happened

The upstream project does one thing, and does it well: back up a Windows directory to a PBS datastore, from the command line. On our side, we needed a tool usable by teams who do not live in a terminal. So on top of that foundation we added a graphical interface, a Windows service that survives reboots, internal scheduling, VSS snapshots and, more recently, fully file-driven deployment with Ansible.

That work is published under GPL-3.0, like the original project. The license therefore required no permission from us for the upstream author to take the code back: he could have done it without asking. He asked anyway. That is a courtesy worth pointing out, and it deserved an equally clear answer: help yourself, and tell us what you need.

The GUI is being backported de-branded

An important detail, and the right way to do it: Tiziano is backporting the graphical interface de-branded. The GUI code goes upstream; the Nimbus Backup name and visual identity stay with us. The original project therefore gets a generic interface for its Windows Proxmox Backup Server client, without our name or our colours — and without leading its users to believe they are installing an RDEM Systems product.

The distinction is a simple one: GPL-3.0 code is meant to be shared, a trademark is not. We did not ask for this; he did it on his own, and that is what makes the whole thing healthy on both sides.

We are giving him a backup volume on our infrastructure

A backup client cannot be tested against nothing. Merging a graphical interface into a PBS client means touching the TLS connection, the certificate fingerprint, API tokens, namespaces, chunking and failure recovery — all of which behave differently against a remote server than they do locally.

So we are giving Tiziano a dedicated test datastore on our NimbusBackup infrastructure, with its own API token, so he can validate his merge under real conditions:

Nothing is attached to that access: no exclusivity, no say over the code, no logo to display. It is a test account for a maintainer taking code we wrote back into his own project.

Why we would rather see this code go upstream

A fork left to live its own life eventually drifts, and the community ends up with two half-maintained clients, two sets of bugs and two sets of documentation. We have nothing to gain from that: our business is not selling Windows backup software, it is running the infrastructure that receives those backups. The better and the more widely adopted the client is — whichever repository hosts it — the better off we are.

It is the same logic as our other contributions: when a fix belongs upstream, it goes upstream. We document those, including a BGP fix accepted and backported into FRRouting, on the RDEM Systems open source contributions page.

Another one, on the Linux side: Proxmox only publishes proxmox-backup-client for Debian. We republish it, without recompiling, signed, in an unofficial repository for RHEL, Rocky, Alma, Fedora, Arch and Alpine, with a guide to install Proxmox Backup Client on another Linux distribution.

What changes for you

If you already use the Nimbus Backup client, nothing moves. Releases keep shipping from our repository, the license stays GPL-3.0, and the Windows binaries stay in the same place. The GUI is now integrated upstream: how the two repositories fit together is described in the 23 September update.

One useful note while we are on the subject of binaries: the client is sometimes wrongly flagged by Windows Defender or SmartScreen. Signing, active since 0.4.1, shows RDEM SYSTEMS as a verified publisher, but the warning may remain until reputation is established. We document the mechanism and the checks (signature, SHA-256, VirusTotal) on our antivirus false positive page.

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