Ouidah ( /ˈwiːdə/), also Whydah /ˈhwaɪdə/ or Juda, is a city on the Atlantic coast of Benin. The commune covers an area of 364 square kilometres and as of 2002 had a population of 76,555 people.

In local tradition Kpase is supposed to have founded the town. This probably happened towards the end of the sixteenth century. The town was originally known as Glēxwé, literally 'Farmhouse', and was part of the kingdom of Xwéda.

In 1727 the Kingdom of Whydah was captured by the forces of King Agaja of Dahomey.

The Portuguese, English, Dutch, and French all constructed forts in the city to protect their interests in slaving. The Portuguese reached the town they called Ajudá in 1580 and the Portuguese Fort of São João Baptista de Ajudá, now housing a museum, dates from 1721 and remained with Portugal until 31 July 1961.

Other attractions in Ouidah include a restored mansion of Brazilian slavers the Maison du Brésil art gallery, a voodoo python temple, an early twentieth century basilica and the Sacred Forest of Kpasse, dotted with bronze statues.