Greetings, Just a quick tabulation. Please advise if you know of other synths to be added to this list. However, please note that I've purposely omitted general-purpose synthesis environments such as Csound, Pd, RtCmix, or SuperCollider, all of which include FM synthesis implementations. I have also omitted non-native solutions, e.g. Airwave-enabled VST instruments. 6PM - Free, open-source. 6-op PM. Cool synth, good sounds. Standalone only. http://sourceforge.net/projects/mv-6pm/ Bazille - Commercial, very unlike the typical DX-oriented FM synths, but very powerful. https://www.u-he.com/cms/bazille Bristol - Free, open-source. 6-op FM. Includes an emulation of the DX7. Cabbage - Free, open-source. Various FM synths, including 3CarrierFM, the ChowningCollection, and FM_Clang. Good stuff ! http://cabbageaudio.com/ Dexed - Free, open-source. 6-op FM. Really nice UI, good sound, huge collection of presets. Btw, I suggest using falkTX's port from his KXStudio repos. https://github.com/asb2m10/dexed Digits - Free, closed-source. A Casio PM emulator, very good sound. Nice presets, but no GUI for the Linux version. http://www.extentofthejam.com/ Hexter - Free, open-source. 6-op FM. My favorite. I prefer it over Dexed, not least because it accepts the sys-ex for my original TX802 patches (Dexed doesn't). Also capable of multi-timbral performance with the Ghostess host. http://dssi.sourceforge.net/hexter.html mda DX10/EPiano - Free, open-source. 4-op FM. Good sound, no GUI, good presets. http://sourceforge.net/projects/mda-vst/ OxeFMsynth - Free, open-source. 4-op FM. Good sound, easy to program, good collection of presets. http://www.oxesoft.com/ Tracktion FM Synth - Commercial. Adds a GUI to the mda DX10. https://marketplace.tracktion.com/app/tracktion-micro-synth-pack.html#.VjdQ… Best, dp