Dexed is an FM-type softsynth developed by Pascal Gauthier of Digital Suburban. It is an ideal application for importing, playing and editing/managing sysex patches from both the classic Yamaha DX7 synthesizer and the TX7.
Dexed includes six operators, faithful to DX structure. Each operator has a level indicator. The operators can be arranged in various algorithms, indicated by the green boxes. Patch banks are called "cartridges" and there are many (about 32) included in the installation package. Selecting a cartridge loads the patches in the relative bank.
Some additional information, including how to interface Dexed with a DX7 hardware unit, can be found on Github HERE.
Some sound banks available at KVR Audio here: Dexed soundbanks at KVR Audio
Dexed at Digital Suburban