From the webpage:
Growthverse was built for marketers, by marketers, with input from more than 100 CMOs.
Explore 800 marketing technology companies (and growing).
I originally arrived at this site here.
Interesting visualization that may result in suspects (their not prospects until you have serious discussions) for topic map based tools.
The site says the last update was in September 2015 so take heed that the data is stale by about six months.
That said, its easier than hunting down the 800+ companies on your own.
Good hunting!