Developer Masaki Ono has created a free, web-based sound & sequence editor for the KORG volca fm2 synthesizer.
Features:
- Full program and sequence editor (with piano roll)
- Manage / back up programs and sequences
- DX7 SysEx import/export
- Sound / sequence preview with the Dexed engine
Availability:
The KORG volca fm2 Patch Editor is available now as a free, browser-based tool.

a clone of the Dexed software?
This looks very cool. IIRC, it was unclear how to import DX7 banks into the latter half of the Volca’s memory, but this looks able to fix that. The sequencing window is extremely promising too. Thank you to the creator of this program!