A good screen size simulator?

[UncleEti1]

Hello, I don't trust too much Firefox web developper screen resizer tool, because, among other things, It does'nt reproduce faithfully my Iphone 4s screen (responsive menu poor display).
I would like some advices ; if there are already some in the tutorials, all respect due, they might be a bit old, and confirmations would be usefull.

Thank you so much.

[Pablo]

Basically, the only thing these 'simulators' do is change the viewport size.
They do not really similate the device.

[UncleEti1]

I see. For example, Resizer is ok with 320 px but not with 1024 px. Ok, I get it. It will be never 100% perfect.

A thread "viewports testing service based on exchange" would be useful, but it's not too clear in my mind how it would work. On an exchange basis I suppose.

A thread with posts like :
-How does look my site with an 800px screen ? Can someone test it for me? .
- I have 320 x, 1024 px and 1280px home and I can tell you roughly (or following a grid..) how your site looks.
This kind of exchange.

Trying to think about it.

Tks anyway.