piano chords: major, minor

— full charts
http://www.piano-keyboard-guide.com/piano-chords.html has keyboard diagrams for

• all 12 major chords
• all 12 minor chords
• many other less relevant [1] chords

[1] because most music sheets use major and minor only.

— sub page on c major chord:
https://www.piano-keyboard-guide.com/c-major-chord.html has details on fingering for all forms of c-major