Guitar Tuner - Free Tune is one of the fastest easiest and accurate tuners
You can easily tune your guitar by using built-in microphone. Works for other string instruments in chromatic mode.

PERFECT FOR EVERYBODY FROM BEGINNERS TO PROFFESEIONALS

Although it optimized for acoustic guitar it can be used for other string instruments or even to find peach of the voice

Chromatic mode:
• Tune to any note on the scale
• Chromatic Mode recognizes each of the 12 chromatic steps of the equal-tempered scale

Pre-Set Tunings:
* Standard Tuning
* Drop D
* Drop C
* Double Drop D
* Open D
* Open C
* Open G
* Celtic tuning

Tuner works in A440 -- the musical pitch corresponding to an audio frequency of 440 Hz which serves as a tuning standard for the musical note of A

App also include chords book with over 2 000 guitar chords and chord variants. Simple design allows you to find chord fingerings and their variants. In addition you can play chords sound to verify you are playing the chord right.

online version of this gitar tuning app:
https://onlinetuner.us