Rithmatic is a DX7-family FM synthesizer and patch library, with a six-operator patch builder you can hear with nothing plugged in. Browse, build and play patches from a library of tens of thousands — connect a Korg Volca FM2 over USB and it becomes a full two-way editor for the hardware too. A LIBRARY THAT SHIPS FULL • 36,118 unique DX7 voices are bundled with the app. No download, no account, no network — they are there the first time you open it. • Search by name, or filter by what a patch actually sounds like: family, character, algorithm, brightness. • Mark favorites, arrange collections, and audition anything — no hardware required. • Every voice is credited to the archive it came from, and to its designer where a bank names one. See the in-app attribution list. PLAY IT INSTANTLY — NO HARDWARE NEEDED • A DX7-compatible synthesis engine runs inside the app, so you can play any patch from the on-screen keyboard. • Every memory pad starts loaded with a real voice from the bundled ROM — open the app and there's already something to play. PATCH BUILDER • Edit all six operators on a graph you can see: the algorithm, the cables, feedback, and each operator's envelope and ratio. • Draw envelopes directly on the amplitude field. • Save to your library, send to the edit buffer, or write to a numbered slot. WITH A VOLCA FM2 CONNECTED • Read the FM2's current patch, send to keys, or write to any of its 64 memory slots. • Back up all 16 sequencer patterns and restore them. • Capture the whole instrument to a snapshot and put it back later. • Import your own banks — standard DX7 .syx and .sys files. BEYOND THE VOLCA FM2 • Set the target to DX7-compatible in Settings and Rithmatic will drive a DX7 (mkI/II), TX7, TX802 or the original Volca FM over standard Yamaha voice dumps. Those are send-only instruments, so the patterns and snapshot features are Volca FM2 only. Rithmatic works offline, keeps your files on your device, and collects no personal data — no account, no analytics, no ads. The library, the patch builder, the pre-loaded pads and the in-app synth all work the moment you open the app, with nothing plugged in. Connect a Korg Volca FM2 over USB and the instrument features unlock too. KORG and volca are trademarks of Korg Inc. DX7 and TX are trademarks of Yamaha Corporation. Rithmatic is an independent app and is not affiliated with or endorsed by either.