Here's a list/mirror of x0xlarge compatible firmwares.
Hex files need to be transfered with USB. Syx files using MIDI. Choose what is easiest for you. Read more about updating here.

• n0nx0x2:
  • Official: n0nx0x2.11.hex | n0nx0x2.11.hex.syx | website
  • 2020 beta build: n0nx0x2_2020beta.hex | n0nx0x2_2020beta.hex.syx
  • 2020 beta build with "double up" feature: n0nx0x2_2020beta_up2oct.hex | n0nx0x2_2020beta_up2oct.hex.syx
    (if you enable DOWN+UP, you get a double octave UP, just like Sokkos and some other firmwares allow. Keep in mind that this is not how a 303 does it and has disadvantages when transposing)
• Sokkos 2.0: Sokkos.hex.syx | website
• MarOS: MarOS_2561_1.82.hex | MarOS_2561_1.82.hex.syx | website
• Adafruit firmware (ported by guest): x0xb0x2.hex | x0xb0x2.hex.syx | website

TODO: Add hex or syx where it is missing.

If you have a custom firmware not listed here, please use the contact form to add it.