Southern Maryland (USA), Skelmersdale United, Southport, Barrow, Stockport County
Karl signed for Widnes in November 2016 on a short-term deal.
Karl originally came through the ranks as a junior at Liverpool before moving to Stockport County at the age of 14, but was released two years later.
Huyton-born Karl moved to the USA to join the college circuit with College of Southern Maryland before returning to the UK, playing for Skelmersdale and then Southport where he enjoyed a successful spell, bagging 24 goals in 140 league games.
Karl then signed for Barrow, where he made 13 appearances as the Bluebirds were crowned Conference North Champions in 2014/15.
In 2015, Karl re-signed for Stockport before leaving in March 2016 to begin a coaching career in America.