Chromatic

Fine-tune your instruments with Chromatic. Chromatic detects the frequency of audio input, converts it to a musical note with the correct semitone and octave, and displays the cents error. Cents are displayed on an analog gauge to make tuning more visually intuitive. Requires PulseAudio or PipeWire.

Flatpak

You can install stable builds of Chromatic from Flathub by using this command:

flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
flatpak install flathub io.github.nate_xyz.Chromatic