Bass players think in intervals more than most musicians -- the root, fifth, and octave form the backbone of nearly every bass line. ChordColor makes those intervals visible on the 4-string fretboard, coloring every position by its relationship to the selected chord root. You can see how a root-fifth pattern in E maps identically to a root-fifth pattern in A, just shifted up a string. That visual consistency is how interval-based fretboard knowledge works.
Two tunings are available for 4-string bass: Standard EADG and Drop D (DADG). Drop D gives you a low D for heavier styles and makes power-fifth shapes on the bottom two strings playable with one finger, just like Drop D on guitar.
Select any chord to see its tones highlighted across the fretboard. The root (red), third (yellow or blue-green depending on major or minor), and fifth (blue) show you the primary target notes for constructing bass lines that lock in with the harmony. Approach notes and chromatic passing tones sit between the colored positions, giving you a roadmap for walking bass lines and fills.