Departement of Val d'Oise has now put on line his main registers regarding genealogy. Created in 1968, it's the farest suburb, north of Paris. Just before Picardy & Normandy. People searching ancestors in the « Great Paris » should also try this web site.
Registers online : "Type de document" Registres paroissiaux (parish registers before 1792) Registres d'état civil (civil status registers from 1793) Tables décennales (alphabetical index, every 10 years from 1800,) Listes nominatives des recensements de population (population census by address) Tables de successions et absences (inheritage index)
Also select :Uniquement documents numérisés (only on line documents)
The 3rd choice (tables decennales) has to be first used to save time.
As always, search has to be done city per city (185) when you know it
For a better understanding, use google translation.