With over 100 million profiles worldwide, LinkedIn is often viewed as the king of online professional networking.

But at least two companies are trying to gain an edge in online networking by tapping the Internet's largest social network: Facebook.

In June 2010, BranchOut was launched in San Francisco, Calif. by Rick Marini, who serves as CEO. At the time when he was planning to build a professional networking site, he realized that the vast majority of the American workforce did not have an online outlet to connect on a professional level.

LinkedIn targets the 10 percent of the workforce that is white collar, Marini told the International Business Times. But entry level workers, nurses, construction workers...those people are generally not on LinkedIn. But they are on Facebook.

So BranchOut turned to Facebook, where three out of every four people in the United States with access to the Internet have accounts. If someone registers with BranchOut, the user can look up a specific company and figure who of their Facebook friends, or friends of friends, works at the company. Then, a user can contact a Facebook friend to help establish a connection with the friend of the friend.

We want to create a professional community for the other 90 percent, Marini said, referring to professionals not on LinkedIn. We want to give them a professional voice for the first time.

Then this summer, Monster Worldwide launched BeKnown, another professional network utilizing Facebook's vast member pool. BeKnown's product leader Tom Chevalier told IBTimes that Monster came to the idea of building the company when Chevalier and other employees realized the vast network of Facebook wasn't being utilized to the extent it could in terms of professional recruiting.

Like Marini with BranchOut, Chevalier said that BeKnown targets a much larger group of individuals than LinkedIn.

[BeKnown] goes well beyond the need of office workers, Chevalier said. People have different types of aspirations.

LinkedIn: A Complement or Competitor?

Both Marini and Chevalier said they view their respective sites as a complement to LinkedIn rather than a competitor, given that LinkedIn has built a niche among white-collar professionals.

BranchOut and BeKnown's best opportunity to gain traction is perhaps among Facebook's younger users. According to research firm comScore, only 11.4 percent of LinkedIn's unique visitors were under the age of 25 as of October 2011. The age brackets of 25-34 years old and 35-44 years old each commanded 24.3 percent of total unique viewers.

However, 27.7 percent of Facebook's unique visitors were under 25. Therefore, young people looking for internships and entry-level jobs are far more likely to be on Facebook than LinkedIn.

In BranchOut's first months, the majority of users were people in their 20s and early 30s. Now Marini said that the average user is now 33 years old, with users primarily in their 20s, 30s and 40s.

Using Facebook as a professional recruiting tool is a very legitimate strategy given Facebook's massive recruiting pool, said Andrew Lipsman, a social media analyst with comScore.

It's like the saying 'you have to fish where the fish are,' Lipsman said.  

In September, LinkedIn had 35.8 million unique visitors, according to comScore, while BeKnown had 332,000 unique visitors. ComScore does not have any data on BranchOut, however AppData, which measures the use of Facebook applications, notes that approximately 660,000 Facebook account holders use the service each month.

Lipsman pointed out that the social networking market is a winner-take-all market. For example, in Facebook's infancy, people were on both Facebook and MySpace. However, eventually the winner took all, and Facebook has become the predominant social media website, with the average user spending 400 minutes a month on Facebook, according to comScore.   

The average LinkedIn visitor spends only 15 minutes on Facebook. But Lipsman said that over the last year, LinkedIn has focused on increasing engagement on their site through features such as the news feed. He believes that if LinkedIn continues engaging people on their site, they can become the winner-take-all company among the white-collar community in terms of professional networking.  

Also, data shows that LinkedIn is slowly beginning to build a brand attracting more than the white-collar executive. According to comScore, 32.3 percent of LinkedIn users in the United States have a household income of over $100,000 annually as of October 2011, compared with 34.7 percent last year. Only 19.5 percent of Facebook users have a household income of over $100,000.

Besides casting a wider net, Marini noted that the relationship a person has with Facebook friends can help foster a professional connection. He pointed out that a person's Facebook friends tend to be people who have close connections to the individual -- a friend, relative or close co-worker-that can help put someone's resume to the top of the hiring pile. Marini said that while people may be close with their LinkedIn connections as well, many LinkedIn connections are between people who met at a conference and talked for five minutes.

Both BranchOut and BeKnown garner revenue through employers posting jobs on the network and recruiters contacting potential job applicants. Creating a professional profile is free.

We want to let our community grow, Chevalier said.  

Separating Personal and Professional Lives

Both Marini and Chevalier noted that many people are concerned that the applications could blur the lines between a person's personal life and professional life. However, each said that their respective services delineates the separate identities. The only information transferred from a person's general Facebook profile to their BranchOut profile is their education and work information.

BeKnown doesn't place a person's pictures or videos in the professional profile. In fact, people can use a different picture for their general Facebook and BeKnown profiles. People can also choose whether they want to show information such as work and education history.

Professional networking on Facebook is new, and establishing the rules of engagement is important, Chevalier said. We don't make any assumptions about how you want to connect.

This story has been updated to provide data for the number of people using BranchOut each month.