Put up to five sections on the same axes and read the difference. The library ships pre-computed Cl, Cd and Cm against angle of attack at a range of Reynolds numbers, so switching a candidate in or out is a click rather than a solver run — and anything the library does not have, NeuralFoil computes on demand.
Lift, drag, moment and L/D against angle of attack, plus the geometry overlay, at whichever Reynolds numbers you select. Comparing at one Re is usually the mistake: a section that wins at Re 500k can lose badly at Re 100k, and plotting both at once is the fastest way to see it.
Drop in a Selig .dat file, pull in a shape from the Kulfan canvas, or load one you saved — custom sections sit on the same axes as the library ones and get their polars from NeuralFoil at the Reynolds numbers you asked for.
Export the shortlist as DXF or Selig .dat for CAD, or carry the winner into the wing designer. Two-dimensional polars are a section property, not a wing property: once the section is settled, induced drag and spanwise loading are the next question.