If you are specifically looking for a free chromatic tuner app that mimics the reliability of KORG hardware, these are top-rated choices:

The AT-2 is a classic, compact chromatic tuner known for its precision and "New Old Stock" appeal. It features: For tuning acoustic instruments.

Allows for tuning electric guitars during a live performance.

A free, lite version of the KORG Gadget 2 music production suite, which includes basic synthesis and utility tools. Free High-Quality Alternatives