With the Chord Calculator, you can look up the most common chords. Select the chord type and press any note to show the chord starting from that note.
If you don't want to hear the chord as you tap a note you can mute the piano with the mute switch in the upper left corner on top of the piano!
If you want to show C# as Db just flip the Sharps/Flats switch in the upper left corner on top of the piano!
You can see the notes spelled out on the right side. The chord will be displayed on the staff as well. The notation is also correct with regards to double flats and double sharps.
In the middle of the screen, you can see the most common notation syntax for the selected chord!