Wiewaswie.nl has data on a lot of places but not on all.... Rotterdam and 's Gravenhage (The Hague) for example are not in there. they have different databases.
Do you know where exactly where your grandad came from?
I don't know wether you like to search for yourself, and you just like to be pointed to the right database, but his birth place is essential for any further search.
If you can give as many details as possible, we can try to get find him and point you to the right starting point.