It’s not every day that Mark Zuckerberg wants to buy your company.

Yet that was the situation faced earlier this year by two young technologists, Joe Hewitt and Blake Ross, who were working on Parakey, a secretive project intended to bridge the gap between a user’s desktop operating system and the internet.

Early in 2007, Zuckerberg, the founder and chief executive of the popular social-networking site Facebook, emailed Ross to invite him to a series of informal get-togethers with other rising Silicon Valley stars that would eventually include YouTube’s Steve Chen and Chad Hurley.

Out of those discussions came the notion that Ross and Hewitt should sell Parakey and come to work at Facebook.

But for Hewitt, 29, and Ross, 22, who earned their Valley cred by helping develop the first version of Firefox, the open-source Web browser that has taken large chunks of market share from Microsoft’s Internet Explorer, the decision was far from an easy one.

“It’s very hard to come to the conclusion that it’s no longer the right call to go at it on your own,” said Ross, a Florida native who got his start in the technology industry at the age of 14 interning at Netscape, in a recent interview.

Every day for a month, Ross and Hewitt debated the pros and cons of the deal, but what eventually sold them on the deal was a development within Facebook.

In May, along with opening the site to all users, Facebook introduced a development platform that would allow any programmer to create applications for use within Facebook.

“Ultimately it was the platform launch that tipped us. It was pretty extraordinary,” Ross said. Within a week of the announcement the pair had decided to sell.

“Mark knows what he’s doing,” said Hewitt of Zuckerberg in a separate interview. “I wasn’t quite clear initially on what he was interested in us for, but as I learned more about his vision for Facebook, it’s clear that he does have one and he’s aggressively executing it.”

While the Facebook deal caused a stir among venture capitalists and on tech gossip blogs, it was mostly regarded as a talent acquisition—Hewitt himself says he has turned down job offers from most of the technology giants, including Google and Microsoft.