Is the Bitaxe open source, and who makes it?

The Bitaxe is genuinely open: the hardware design files (schematics + PCB) are published, and the firmware — AxeOS, part of the ESP-Miner project — is open-source code you can read, build and flash yourself. This is different from commercial miners, where the firmware is closed and the internals undocumented.

The original design is by skot9000. Day-to-day stewardship — firmware maintenance, the many hardware revisions, and community support — runs through the Open Source Miners United (OSMU) community. Because the design is open, there is no single official seller: many independent builders and small shops produce compatible Bitaxe and Nerd-family boards. When buying, the community maintains a vendor list to help identify genuine builds.

This openness is the whole point: it stands on the shoulders of the open-mining work that came before it, and lets anyone verify exactly what the device does.