Useful Guitar Tools

FREE

https://tuxguitar.en.softonic.com/

http://www.fachords.com/guitar-learning-software/ (Great blog, as well)

http://www.musictheory.net/exercises/ (I especially like their interval ear trainer)

https://www.earmaster.com/products/free-tools/interval-song-chart-generator.html

http://virtualpiano.net/

https://www.songsterr.com/ (also has a paid plan with more features)

https://chordsterr.com/

http://www.scales-chords.com/scalefinder.php

https://www.metronomeonline.com/

Or if you prefer a more advanced metronome:
https://www.infiniteguitar.com/online-metronome

PAID

https://www.jamplay.com/

https://www.guitar-pro.com/en/index.php

http://sites.fastspring.com/robert/instant/bounce (a progressive and full-featured metronome)

https://www.songsterr.com/a/wa/plus

https://www.earmaster.com/

https://www.ronimusic.com/amsldowin.htm (Windows)

https://www.ronimusic.com/amsldox.htm (Mac)