Every app shows golden hour times. None tell you if it'll be any good.

Golden hour timing is trivial — it's when the sun sits between −4° and +6° altitude. Golden hour quality is a cloud-structure problem, and it comes in two distinct flavors worth planning for separately:

• The dramatic sky. You want a canvas of mid or high cloud (roughly 20–80% cover) for the low sun to light from below — and a clear low horizon in the sun's direction so the light can get under it. Total overcast kills it; so does a sterile clear sky. The burn happens when low cloud stays under ~40% while something higher up catches fire.
• The clean light. For portraits, product shots and unbroken warm side-light you want the opposite: total cloud under ~20%, no rain, sun in the band. Boring sky, perfect subject light.

ShootWindow scores both as separate recipes — Dramatic wants the canvas, Clean wants it empty — across every morning and evening in the forecast, using layered cloud data (low/mid/high) rather than the single "cloudiness %" number that hides exactly the structure you care about.