The most useful tool I've found is Perfect Ear for Android and iOS. It's not as full-featured as GNU Solfege, but it covers all the important stuff and it's far

The most useful tool I've found is Perfect Ear for Android and iOS. It's not as full-featured as GNU Solfege, but it covers all the important stuff and it's far easier to dip into when you have a spare moment. https://www.perfectear.app/ https://www.perfectear.app/ If you're a late beginner/early intermediate player and trying to move past the chord shapes and scale patterns rut, I strongly recommend William Leavitt's A Modern Method for Guitar. It's hard - really damned hard - but it's logical, the difficulty curve is fairly linear once you get past the shock of traditional notation, it inculcates good habits from the outset and it provides you with a very broad base of technique that is applicable to all styles of guitar. https://www.amazon.com/Modern-Method-Guitar-Volumes-Complete/dp/0876390114 https://www.amazon.com/Modern-Method-Guitar-Volumes-Complete...