In late 2013, web security expert Troy Hunt was analyzing data breaches for trends and patterns.
He realized breaches could greatly impact users who might not even be aware their data was compromised, and as a result, began developing HIBP. "
Probably the main catalyst was Adobe," said Hunt of his motivation for starting the site, referring to the Adobe Systems security breach that affected 153 million accounts in October 2013.

Hunt launched Have I Been Pwned?
on 4 December 2013 with an announcement on his blog.
At this time, the site had just five data breaches indexed: Adobe Systems, Stratfor, Gawker, Yahoo!
Voices, and Sony Pictures.
However, the site now had the functionality to easily add future breaches as soon as they were made public:
Now that I have a platform on which to build I'll be able to rapidly integrate future breaches and make them quickly searchable by people who may have been impacted.
It's a bit of an unfair game at the moment – attackers and others wishing to use data breaches for malicious purposes can very quickly obtain and analyse the data but your average consumer has no feasible way of pulling gigabytes of gzipped accounts from a torrent and discovering whether they've been compromised or not.

— Troy Hunt
In late 2013, web security expert Troy Hunt was analyzing data breaches for trends and patterns. He realized breaches could greatly impact users who might not even be aware their data was compromised, and as a result, began developing HIBP. "Probably the main catalyst was Adobe," said Hunt of his motivation for starting the site, referring to the Adobe Systems security breach that affected 153 million accounts in October 2013.
Hunt launched Have I Been Pwned? on 4 December 2013 with an announcement on his blog. At this time, the site had just five data breaches indexed: Adobe Systems, Stratfor, Gawker, Yahoo! Voices, and Sony Pictures. However, the site now had the functionality to easily add future breaches as soon as they were made public:
Now that I have a platform on which to build I'll be able to rapidly integrate future breaches and make them quickly searchable by people who may have been impacted. It's a bit of an unfair game at the moment – attackers and others wishing to use data breaches for malicious purposes can very quickly obtain and analyse the data but your average consumer has no feasible way of pulling gigabytes of gzipped accounts from a torrent and discovering whether they've been compromised or not.
— Troy Hunt
Have I Been Pwned?