There’s no substitute for getting a handle on music theory and learning your scales, but if you need a quick online reference source, ToneGym’s free Music Scales Tool could come in very handy indeed.
Designed to give you a better understanding of scales/chords and how they’re played, this enables you to select the root note/tonic and start exploring. You can play back diatonic modes and harmony chords (triads, 7ths, 9ths, 11ths and 13ths) and also a whole roster of non-diatonic scales.
There’s a scale finder, too - select your choice of notes and you’ll be presented with the scales that contain them.
As the scales and chords are played back, they’re also visualised on the graphical keyboard, so you can learn them, too. The tool should help you to get a better understanding of the relationship between scales, potentially improving your songwriting in the process.
You can access the free Music Scales Tool right now on the ToneGym website.