Fretello - Duolingo for learning how to play guitar
MuseScore.org - Create, play back and print beautiful sheet music with free and easy to use music notation software MuseScore. For Windows, Mac and Linux.
Justin Guitar - Over 750 completely free guitar lessons!
Guitar Pro 7 - Create, play and share your tabs
Uberchord Guitar - Get better on your guitar. Fast.
Finale - Finale, the world standard for music notation software, lets you compose, arrange, notate, and print engraver-quality sheet music.