tl;dr: Guitoro is a free browser-based virtual guitar that you strum with your keyboard (left hand on chord keys, right hand on H/J to strum) or by swiping on a touchscreen, using recorded samples from four real instruments (acoustic, classical, electric, bass). It includes 15 chords in every key, 56 strum/picking patterns, a backing band, and 51 songs that can be slowed to 20% speed, with on-screen visualization of strings hit, pick direction, and finger positions. Intended as both a playable instrument and a learning aid for real guitar, with chord shapes, tunings, capo support, and recording built in.