NetLimiter is described as 'An advanced Windows tool for internet traffic control and monitoring. Set speed limits for apps and connections, with real-time and long-term stats' and is a popular Firewall in the network & admin category. There are more than 25 alternatives to NetLimiter for a variety of platforms, including Windows, Linux, Mac, Android and iPhone apps. The best NetLimiter alternative is Portmaster, which is both free and Open Source. Other great apps like NetLimiter are simplewall, NetBalancer, Fort Firewall and Little Snitch.
Portmaster does not provide a way to set bandwidth limits, so it is not similar enough to NetLimiter to be an alternative.