guitarLayers - guitarLayers is a professional macOS guitar learning software.
MyGuitarTuner.com - Online microphone tuner for guitar, ukulele, violin and other instruments. Tune by ear or using the microphone of your device. It's fast and accurate algorithm makes it one of the best online microphone tuners available.
Fachords - Fachords is an online site that provides many resources that you can use to take your guitar skills to the next level.
Fine Tuner - Fine Tuner is a minimalistic guitar tuner that utilizes your device's built-in microphone.
TrueFire - The Best Guitar Lessons Online Fast. Easy. Fun.
Metronomus - Powerful and beautiful online metronome