Another simple app by Robota Softwarehouse source generates tones so you can tune your guitar. A nice interface allows you to select the note easily and shows which string you are tuning by coloring it blue. The tone lasts for about 6 seconds and you can mute it sooner if you’d like by hitting mute or go to another note by tapping on it. There is also a volume control. The only thing this app needs is a little smoother sound. There is a click when the tone turns on and off.