In 2011, dubstep gained significant traction in the US market, by way of a post-dubstep style known as brostep, with the American producer Skrillex becoming something of a poster boy for the scene. In September 2011 a Spin Magazine EDM special referred to brostep as a "lurching and aggressive" variant of dubstep that has proven commercially successful in the United States. Unlike traditional dubstep production styles, which emphasise sub-bass content, brostep accentuates the middle register and features "robotic fluctuations and metal-esque aggression". According to Simon Reynolds, as dubstep gained larger audiences and moved from smaller club-based venues to larger outdoor events, sub-sonic content was gradually replaced by distorted bass riffs that function roughly in the same register as the electric guitar in heavy metal.
The term brostep has been used by some as a pejorative descriptor for a style of popular Americanised dubstep. So called "dubstep purists" leveled criticism at brostep because of its preoccupation with "hard" and aggressive sounding timbres. U.S. and Canadian artists often drew inspiration from British brostep producers who tended to work less with sub-bass and more with mid-range sounds such as Caspa and Rusko, and Vex'd. Rusko himself claimed in an interview on BBC Radio 1Xtra that "brostep is sort of my fault, but now I've started to hate it in a way ... It's like someone screaming in your face ... you don't want that." According to a BBC review of his 2012 album Songs, the record was a muddled attempt by Rusko to realign his music with a "Jamaican inheritance" and distance it from the "belching, aggressive, resolutely macho" dubstep produced by his imitators. Commenting on the success of American producers such as Skrillex, Skream has stated: "I think it hurts a lot of people over here because it's a UK sound, but it's been someone with influences outside the original sound that has made it a lot bigger. The bad side of that is that a lot of people will just say 'dubstep equals Skrillex'. But in all honesty it genuinely doesn't bother me. I like the music he makes."
Other North American artists that have come to be associated with the brostep sound are Canadian producers Datsik and Excision. Their production style has been described by Mixmag as "a viciously harsh, yet brilliantly produced sound that appealed more to Marilyn Manson and Nine Inch Nails fans than it did to lovers of UK garage".
The heavy dubstep sound has also attracted the attention of metal bands. Nu metal band Korn's 2011 album The Path of Totality features several collaborations with electronic music producers, including dubstep producers Skrillex and Excision. The term metalstep has been used for a fusion of dubstep and metal. Other artists who have been put under the metalstep genre includeCelldweller, who is noted for his fusion of many electronic elements, including dubstep, mixed in with heavy guitars and other metal instruments.