Deep, with a hard front.
There is a click at the start of every note and real weight behind it, so the line still reads on laptop speakers that cannot produce the low end at all.

A deep, punchy bass that opens up the harder you hit it.
No MIDI keyboard? Play with your computer keys: bottom rows are the lower octave, top rows the higher one. Hold Shift to sustain. ← → octave, ↑ ↓ semitone.
Online bass
There is a click at the start of every note and real weight behind it, so the line still reads on laptop speakers that cannot produce the low end at all.
Play harder and it brightens: one sound responding to you, not two different ones. A MIDI keyboard makes that far easier to control than letter keys.
Press Record, play, then Stop, and download it as a WAV to keep or use elsewhere. The file is made on your own computer.