Openterface, Cytrence and Sipeed make a KVM over USB product. I have bought the cheapest one: the Sipeed NanoKVM-USB at about EUR 60 (available on Amazon) which includes all nessecary cables. I love the product as it allows me to do repairs and upgrades on any laptop or desktop PC I put on my desk, without having to connect a second monitor keyboard and mouse.
Data-center usage
This device may not be ideal in the data-center as a permanently installed KVM, as it has no network connection. If you would have one management node, you could install a bunch of these in that node to control the other rack-servers (without opening a new attack surface). It may also be of great help when visiting a (private) data-center. I would always want to have this KVM (and a HDMI to VGA adapter) in my laptop bag as it takes barely any space and may avoid the need of a crash cart in the cold aisle.
SBC and computer repairs
For debugging single-board computers (like Raspberry Pi, Orange Pi, etc.) and repairing PCs in general, the NanoKVM‑USB shines because it works before networking and drivers are available. You plug HDMI from the target into the NanoKVM and a single USB into the target for keyboard/mouse HID, then operate everything from your laptop as if a local monitor and peripherals were attached. That makes BIOS/UEFI or GRUB changes, OS installs and fixing boot problems straightforward without hunting for a spare screen or keyboard. It’s also ideal for machines with broken displays or keyboards, or for air‑gapped systems as it has a switch to toggle a USB drive between host and target.
Build quality
The NanoKVM‑USB’s plastic side panels are glued to the aluminium casing rather than fastened with screws. In practice, pulling a tight HDMI or USB cable straight out can loosen a panel, exposing the Sipeed mainboard. It’s something to be aware of when disconnecting cables. Support the panel near the connector and pull gently to avoid popping the side off. On the plus side, sliding the mainboard out lets you see exactly how the ingenious design is put together in such a small device, which is both educational and reassuring. If a panel does come loose, a tiny dab of superglue on the inside lip will probably fix it.
Linux software
The host application is open source and distributed as a convenient Debian package on GitHub releases, which makes installation on Debian‑based systems (Debian, Ubuntu, Linux Mint, etc.) straightforward. In daily use it generally works flawlessly, but occasionally the app won’t detect the USB HID keyboard/mouse emulator after you connect the device. If that happens, just unplug and reconnect the NanoKVM‑USB to the host to fix this problem. Other than that the software works with very low latency and is very reliable.
Privacy and security
The NanoKVM‑USB has almost no firmware. The screen capture device presents itself as a standard webcam. The USB HID emulator operates via a USB connected serial port. This minimal design means there’s little software to attack. The device also has no network connection. It cannot be reached over the internet. This makes it much less vulnerable than network‑based KVM solutions. The open source software is verifiable and makes no internet connections. This is crucial when installing machines with disk encryption. Privacy is very important in such scenarios. For security‑conscious users this is a major advantage.
Conclusion
At roughly EUR 60 the NanoKVM‑USB is a must‑have for anyone who installs or repairs machines regularly and cares about privacy and security. You get good build quality, open‑source and reliable Linux software, and responsive, low‑latency control in a tiny package. The side panels that can come loose if you pull a cable too hard, and the occasional need to reconnect the device to detect the USB HID are acceptable minor flaws that are easy to work around. Overall, it’s a joy to use and has earned a permanent place in my toolkit.