Simply supported beams are statically determinate structures. This online calculator is very useful for shear force and bending moment calculations for simply supported beam.
You can calculate support reactions, shear force and bending moment at any section as well as maximum bending moment and its location.
This calculator is useful for 14 different loading cases of point load, uniform load, varying load or pure moment.
The calculator is available at https://civilengineer.webinfolist.com/mech/bmcalc.htm