Rob McGovern launched two successful companies (ever hear of CareerBuilder?) and bounced back from a horrific car accident a few years ago. But the serial entrepreneur says the app he launched last month may just be his biggest accomplishment yet.

Cobrain combines 400 of the biggest retailers into one mobile and desktop app and lets users buy directly from merchants. It makes suggestions based on what the user and others with similar tastes have said they like. Users can also get alerts of when items are on sale. CareerBuilder, which he launched in '95 and sold for $680M, grew to 23 million users per month, and Rob says, “this will be bigger.” The app hasn’t had any marketing yet, but it will when beta testing is complete. Regardless, its user numbers are doubling every two days.

Rob, who also founded Jobfox, says bringing together cross merchant data is the biggest challenge. The same scarf sold by five merchants will have five different names and unit numbers. The process is called product entity resolution, and Rob says no company has been able to do this with 400 merchants. Cobrain "knows" 5,000 brands and over 7 million products. The Bethesda-based team of 12 includes a handful of data scientists who have built algorithms that can process product info sent daily from its network of merchants. The merchants pay Cobrain a 5% to 10% commission on sales generated by its personalization engine. Rob says it's similar to a Google Adwords pay-per-click model.

Retailers like Bloomingdale’s and Macy’s have reacted well to the service, considering 92% of web visitors go to a retailer's site and do nothing. Adding recommendations that increases the chance of a consumer making a purchase is huge, says Rob. Cobrain will soon announce two big partners and expects to double the company’s size by December. The US apparel market is $300B and growing 3% per year. The online apparel market is $80B and growing 15% annually. As far as his health post car accident, Rob says he’s the luckiest person in the world.