Janne is a common given name in the Nordic countries and Estonia. In Denmark, Norway and Estonia it is considered a feminine name (a short form of Johanne), while in Sweden and Finland it is considered masculine. In Sweden and Finland it is often used as a nickname for people with related (male) names based on Johannes such as Jan, Jean or Johan. The name's origins lie in the ancient Hebrew names Yohanah/Yohanan (feminine/masculine), meaning "Yahweh (God) is gracious". The name spread to Greece along with Christianity, and became Ioanna/Ioannes.
https://en.wikipedia.org/wiki/Janne