Upload an image of your dried saliva and you will learn if you are in your fertile days.
It is scientifically proven that blood, urine and saliva (mucus) predicts ovulation in real time circa 3-5 days ahead from estrogen level increase.
Saliva test is reusable and affordable. It only requires a microscope, while blood and urine tests require expensive hormone strips.
Other tests, e.g. basal body temperature tests, predict ovulation with a software algorithm.
You can monitor your fertile days in real time for an affordable price.