Input a key signature, Roman numeral, and figured bass, then hit "search" to see chordal members and doubling rules!
P.S. This program will only return results for seventh chords with dominant function (V7/viiº7 and their inversions) and those built on scale degree 2 (ii7/iiø7/iiº7) since they are typically the only ones found on the AP Music Theory exam.