The Nidda is a right-bank tributary of the river Main in Hesse, Germany.

It springs from the Vogelsberg on the Taufstein mountain range near the town of Schotten.

It flows through the Niddastausee dam, and then through the towns of Nidda, Niddatal, Karben, and Bad Vilbel.

The original numerous meanders turned into bayous, while the riverbed was straightened and made deeper.

Since 1993, the Nidda gets partially restored to its natural state, beginning in Frankfurt-Berkersheim.