At that revenue number and with no innovation and no R&D (zero employees), seems like a no brainer for some smart hacker to replicate and provide the same service for less.
BuiltWith is 16 years old. Their business has been fully commoditized and ripped off so many hundreds of times that most of these "competitors" don't even have names. They're just email addresses in your spam folder. I have literally hundreds of mails that look like this -- "hey, wanna buy a list of every site using your competitors' services, enriched with business info and key employee contacts?".
The "$14M ARR" appears to be a journalist's guess/estimate of the company's revenue in 2015, which Gary said was an exaggeration, per https://www.ipobase.com/builtwith/
I would bet that BW is long past peak revenue now.
It sorta seems like they won the 'right place at the right time' lotto in getting the links on about us. A competitor might have a huge battle to win that market share.
At that revenue number and with no innovation and no R&D (zero employees), seems like a no brainer for some smart hacker to replicate and provide the same service for less.