A free program for Android, by Ukulele Wave.

Developed by UkuleleWave, Ukulele Tuner Pocket is a free music tuner that’s specifically meant for ukuleles.

Using your mobile device’s build in microphone, you can now utilize this app to fine tune your ukulele so that you get the perfect pitch. It’s easy to set up and tune: select the soprano setting if you are focused on the treble. Opt for the baritone setting if you want to go low.

This tuner is designed to be compatible with every ukulele type: soprano, concert, tenor, baritone, Hawaiian, and Bass.  

This tuner is also designed to work with precision, with its selection of simple functions, as well as target frequencies (Hz) that you can either show or hide.