GSi describes Key Performer as "the Swiss Army knife of the modern gigging keyboardist". It's a single software instrument which offers a wide variety of keyboard sounds that are used in almost all musical genres where a keyboardist is involved.

To summarize a few of its key features, it offers:

• Several classic keyboard sounds including pianos, electric pianos, synths, organs, etc.
• A sample playback section (aka "ROMpler") with "adaptive playback".
• A physical modeling classic Electric Piano.
• A physical modeling "Wurly" piano.
• A phase modulation synthesizer for the famous DX Piano.
• A Virtual Analog polyphonic synthesizer.
• A Virtual Tonewheel Organ with rotary speaker effect.
• Two effect slots with all the most famous effects.
• An AMP simulation section with overdrive.
• A global Reverb effect.
• 64 Programs per bank, 9 snapshots for organ sections and 9 for VA synth.
• Full MIDI implementation.
• Easy MIDI Learn.
• Huge efficiency with very low CPU power requirements.
• Simplicity of use: "Versatility, Stability, Expandability, Authenticity".