Riksarkivet

Search in the National Archives' digital archives, indexes and databases. You can also search for information about archives and archival institutions in Sweden.

The link above is for staff and students at Linnaeus University. If you are not affiliated with the Linnaeus University, go to the National Archives' home page instead and select Search the collections. The content is freely available to everyone, but you need to create an account to access content younger than 110 years.