In ITA Matrix there is an advanced routing code for filtering entire countries. Just enter ~l:nUS+ in the routing codes section to avoid layovers in USA for example.
This is where you enter the routing code.
These are the results without any routing code.
These are the results when specifying no layovers in USA.
Which sites exist ?
Quite likely none since it's a non-sensical search. There are 420 major/medium airports in South America and 1026 in Europe, which creates over 42000 possible combinations. I imagine you can hit pretty much all of those with two connections and maybe 25% with a single connection. That's still over 10,000.
It's just not practical to ...
The website http://matrix.itasoftware.com/ (owned by Google) supports this a bit, but you need to learn how to use it for complicated question like this.
In a nutshell, you enter a city pair from about the middle of your starting area to about the middle of your target area, and then choose to allow 'all airports within x miles' (1000 or whatever you want). ...
It's showing as $1905 for me now.
I run an OTA (Beat That Flight) and play with dates/prices a lot. Sometimes you get error fares where an OTA or provider genuinely has the wrong price (They've often forgotten fuel costs or tax or conversions). There are whole sites dedicated to finding these as they tend to not last long.
In that case, it was either an ...
Nowadays even on long-haul flights many airlines have fares with no luggage included. Lufthansa for instance has an "Economy Light" fare like this.
Some search engines will allow you to specify if you want only fares which include luggage.
Note also that pricing can be weird. I made a random search on the Lufthansa site, and the "Economy Light&...
As other answers have mentioned, there are numerous sites offering this. However, all those are showing you which is the cheapest day to buy a flight now. This allows you to find a low price but those may not be the lowest prices because it is highly likely that purchasing the same flight a different day comes to a different price.
Instead of doing the ...