Free tool
Chord transposer
Move a progression into the singer's key. Chords come out spelled the way the new key is written: Db not C#, F#m not Gbm.
In the key of A
AE/G#F#mD
AEDA
Know it in every key
Transposing on paper is the easy part.
Playing it in the new key is the hard part. Earshed's any-key challenge picks a key you haven't played a song in, shows it as numbers, and follows you on your keyboard until you've got it.