In Amsterdam as a starter you can expect somewhere between €30k and €38k, depending on your skill set and company you're applying for. I think €45k for a senior position sounds about right, but this really depends a lot on where you're going to live: cost of living in for example London is much higher than somewhere in Spain.
As an indication for taxes: €45k before taxes would probably be around €30k after income taxes in the Netherlands.
I've seen financial companies offering around 40k for starting developers. I would think 30k is a bit low for a university graduate, most offers will be around 32k - 35k I guess. 45K euro for a senior dev sounds really low to me though!
As an indication for taxes: €45k before taxes would probably be around €30k after income taxes in the Netherlands.