I think it’s Finland. I’m in Sweden and I’m almost sure that my compensation is not public. What you can do IIRC is to request a credit check on someone which would contain the income and the tax paid but then the person is notified who requested the data. Typically this is done when you apply for a mortgage.
For example, in Sweden, you can get a 'tax calendar' (a bit like an old-fashioned phonebook, but with total pay instead of phone numbers). You can buy relevant pages conveniently online.
