Is there any utility like `Proxifier` for Ubuntu?

According to the description of the homepage of Proxifier, the software Privoxy looks like a good recommendation. Privoxy is a proxy application which filters a lot privacy related things (cookies, webbugs etc.). However the software allows you to configure HTTP, SOCKS and other types of software and is very flexible. I am sure that this is a good replacement.

After reading your comment I can go a bit more into detail: The central configuration file is /etc/privoxy/config. The directory /etc/privoxy has some other files, too. The config file is very well documented.

Lets assume you want to send all traffic to example.com though proxy-a and all traffic to askubuntu.com through proxy-b. SSL/TLS traffic (HTTPS) should not use any proxy. So you add the following lines:

forward .example.com proxy-a
forward .askubuntu.com proxy-b
forward :443 .

The keyword forward is followed by a site or a pattern. It can be an IP address, hostname or a regular expression. All traffic which matches will be send to the last entry in the line. This the proxy address. When you use a . (a dot) a the end of a line, it means that the pattern before will not use any proxy. You will find more information at the handbook.

you can use tsocks or dante

I know its a very old question. But i'll answer it for anyone that is still looking for a good "Proxifer" alternative.

Redsocks seems to do a good job!.

http://darkk.net.ru/redsocks/

I set it up to route to multiple socks proxies. Example config from /etc/redsocks.conf below:

redsocks {
local_ip = 127.0.0.1; ip = 127.0.0.1; type = socks5;
local_port = 11081;
port = 1081;
}
redsocks {
local_ip = 127.0.0.1; ip = 127.0.0.1; type = socks5;
local_port = 11082;
port = 1082;
}

Then setup iptables to route to the different ports

iptables -t nat -A REDSOCKS -d 192.168.220.0/23 -p tcp -j REDIRECT --to-ports 11082

iptables -t nat -A REDSOCKS -d 192.168.234.0/23 -p tcp -j REDIRECT --to-ports 11081

iptables -t nat -A OUTPUT -p tcp -m owner --uid-owner luser -j REDSOCKS