Rap Genius has been named No.1 in the music category of Fast Company's 2013 list of the world's most innovative companies, with streaming service Spotify coming in second.

The self-named "hip-hop Wikipedia” has been given the top spot for “explicating the rap canon, then moving on to everything else”. The site crowd-sources annotations of rap lyrics while deciphering slang and unpacking references.

Last October, Rap Genius scored investment of $15 million from Silicon Valley venture firm Andreesen Horowitz. It has ...