Software for drawing intervals

Question

Is there some tool or website to draw intervals like this?

It would also be helpful if I can draw more than one interval in order to see the intersection of $2$ or more intervals.

Answer 1

Mathematica

      Graphics[

     {Red, BSplineCurve[{{-30, 10}, {-6.1, 10}, {-6, 0}}], 
      Green, BSplineCurve[{{-6, 0}, {-1, 18}, {5, 0}}], 
      Blue, BSplineCurve[{{5, 0}, {10, 11}, {20, 10}}],
      Black, PointSize[0.02], 
      Point[{-6, 0}], Point[{5, 0}]}, 

      Ticks -> None,
      Text[Style["x", 28, Italic, FontFamily -> "Times"], {22, 0}]},
      Axes -> None]

By the way, Mathematica has wonderful tools for drawing intervals, with lots of style variations, but alas none like the BSpline curves you desire (which, frankly, I've never seen).