Alternate Chord is a very powerful and excellent music score chords tool designed specifically for practicing guitar chords and guitar scales, developed by Alternate Tools from Germany. It has a clear and intuitive interface, includes a variety of different chords, allows the addition of your own scales and chords, and provides the possibility to listen to scales/chords through the MIDI interface. Better yet, it's free and open-source.

When three or more different notes are combined in a certain way and played at the same time, they are called chord. Learning the guitar must first learn the chords. But there are so many guitar chords, it is impossible to remember all of them at once. If you want to search for guitar chords on your computer, try Billion Chords, a well-known guitar chords querying tool.