Open-source Bitcoin miners: what is open on the Bitaxe, Nerdaxe and NerdQaxe

An open-source Bitcoin miner is ASIC mining hardware whose board design and firmware are public, under a licence that allows anyone to build and modify them. That holds for most of the miners we sell, for a few only in part, and for the Avalon Nano 3S not at all. Below you will find, for each device, where its board files and firmware live and which licence applies, followed by what open-source mining lets you do in practice.

What can be open on a miner

A Bitaxe is a circuit board carrying one or more mining chips (ASICs), the voltage supply for those chips and an ESP32-S3 that runs WiFi, the fan and the web interface. Two parts of that can be open:

• The board design. The Bitaxe Gamma repository, bitaxeorg/bitaxeGamma, holds the KiCad project with schematic and layout, the schematic as a PDF, a bill of materials, Gerber files for production, 3D data and assembly notes. With these you can have the board made, change it or compare it with the unit on your desk.
• The firmware. The code on the ESP32-S3 sets clock and voltage of the ASICs, controls the fan, keeps the WiFi and pool connection (Stratum) alive and serves the web interface. Each version is published as a release with ready-made files for every supported board.

What stays closed

The mining chips are closed components on every miner. The BM1370, BM1368 and BM1373 come from Bitmain, the A3197 in the Avalon Nano 3S from Canaan, and neither manufacturer publishes how the chips work inside. The ESP32-S3 is also a finished chip from Espressif, although its development framework ESP-IDF is open under the Apache-2.0 licence. What is open on an open-source miner, then, is the board around the chips and the software that drives them.

Three of our products come with caveats:

• Nerdaxe Gaia and Gaia Copper Pro: up to our check date we found no published board files for the Gaia, and it is not on the Bitaxe project's list of open miners either. Its firmware is open.
• NerdOctaxe Hydro: we found no repository of its own for the water-cooled version. Its firmware is open.
• Avalon Nano 3S: it has a web interface without a cloud account, but neither firmware nor board is public. Its chip, the A3197, is now used by an open design from the Bitaxe project (bitaxeorg/bitaxeAva, CERN-OHL-S-2.0); that does not make the Nano 3S itself any more open.

Two licences: CERN-OHL-S and GPL-3.0

Most boards are published under the CERN Open Hardware Licence Version 2, Strongly Reciprocal (CERN-OHL-S-2.0). It lets you use the design, modify it, manufacture from it and sell the devices. In return, anyone who passes on hardware based on a modified design has to make the modified source files available under the same licence. Two of the designs in the table below use the GPL-3.0 instead.

The firmware is licensed under the GNU General Public License 3.0 (GPL-3.0). If you distribute modified firmware, as a file or on devices, you have to provide its source code under the GPL-3.0 as well. That is why our own builds are public on GitHub too. The licence text in each repository governs the details; this summary is not legal advice.

Our miners and where their sources live

We map devices to repositories using the list of open miners that the Bitaxe project maintains itself (bitaxeorg/foss-miner-list). The licence shown is the one GitHub reports for each repository.

AxeOS and NerdOS

AxeOS is the web interface of the ESP-Miner firmware from the Bitaxe project (bitaxeorg/ESP-Miner). It runs on every Bitaxe board we sell, from the Gamma 601 to the Gamma Hex 1300. On our check date the current version was 2.15.4, released on 21 October 2026.

NerdOS is the firmware of the Nerd devices, maintained by shufps in ESP-Miner-NerdQAxePlus. According to the repository it started as a fork of the NerdAxe firmware, itself derived from ESP-Miner, and was reworked for the NerdQAxe+. The latest regular release on our check date, 1.1.0.1 from 24 September 2026, ships images for the Nerdaxe, NerdQaxe and NerdOctaxe. The Nerdaxe Gaia is so far only supported by pre-releases of the 1.1.1 series.

Day to day you use both the same way: web interface at the device's IP address, pool and address in the settings, clock and voltage set by hand. The difference is the hardware they know. Each factory image is built for one board, and each firmware family only knows its own hardware. So AxeOS does not belong on a NerdQaxe, and NerdOS does not belong on a Bitaxe. The firmware of your device is listed under Firmware on its product page. How to adjust clock and voltage in small steps is shown in AxeOS tuning.

OSM-OS: our forks

We maintain a fork of each firmware line: OSM-OS-Bitaxe, based on bitaxeorg/ESP-Miner, and OSM-OS-Nerdaxe, based on shufps/ESP-Miner-NerdQAxePlus, both under the GPL-3.0. The main changes are per-device defaults, for example 625 MHz at 1200 mV for the Bitaxe Gamma 601, 750 MHz for the Gamma Copper Pro and 550 MHz at 1250 mV for the Supra Hex 702. Both also come with a pool and a payout address filled in: pool.bitaxe.de, with pool.opensourceminers.de as the fallback, and a fixed Bitcoin address. After a factory install, swap in your own address; until then, a block your miner finds would be paid to the stored one. The Bitaxe fork also adds an update check that finds new OSM-OS versions, plus individual fixes listed in the release notes, such as one for the BOOT button, which had stopped responding as of ESP-Miner 2.15.2.

You can check exactly what differs, file by file: the comparison of ESP-Miner 2.15.4 with OSM-OS 2.15.4-osm covers 41 files, most of them configuration files for individual boards. Our firmware flasher installs both forks from the browser and checks every file against its GitHub release with SHA-256 before writing it. After a factory install, enter your own Bitcoin address in the settings.

What an open miner lets you do

• Pick any pool: enter any pool that speaks Stratum, including your own with a Bitcoin node and pool software such as public-pool. No manufacturer has to approve it. Addresses and fees of the solo pools are in the solo pool comparison.
• Build the firmware yourself: both repositories document how to build with ESP-IDF, optionally inside a Docker container. That way you can change a default, add a feature or fix a bug and flash the result. If you pass your image on, the GPL-3.0 requires the source code to go with it.
• Repair it: the schematic and bill of materials tell you which component sits where and what replaces it. Fans and coolers come in common sizes, the Gamma 601 for instance uses a 40 mm fan, and you can fit cooling upgrades such as the ICE Tower Low Profile or the AXP90 Copper Pro yourself.
• Read before you update: what a new version changes is in the release notes and the source code, so you know what goes onto your device.
• Keep using it: the firmware does not depend on a single manufacturer. Forks like ours show that anyone can keep maintaining the code.

Further reading

To get an open miner running, follow setting up a Bitaxe or setting up a Nerdaxe. What it costs to run at home, how loud it is and where to put it is on the home mining page. The miner comparison lists every device with hashrate and power draw, and about us explains who is behind Open Source Miners.