LC Filter design
LC Filter calculator: https://rf-tools.com/lc-filter/
Enter filter topology, order, input/output impedance, cutoff frequencies, and ripple requirements
Outputs the either the exact or the nearest standard component values needed to implement the filter, along with a schematic of the filter and a bode plot of the frequency response
Switching Power Supply Filter Design app notes: https://www.ti.com/lit/an/snva538/snva538.pdf (edited)
Section on parallel damped filter is a good reference on how to use damping resistors to eliminate resonance from a passive LC filter