San Francisco social media company Twitter Inc. has purchased Cambridge start-up Bluefin Labs, its second acquisition of a local technology company in just over a week.
The two deals give Twitter a local outpost in Cambridge and about 75 employees here.
Terms of the deal to purchase Bluefin Labs were not disclosed.
The company, which spun out of the Massachusetts Institute of Technology’s Media Lab in 2008, had raised $20.4 million from investors such as Time Warner Investments and SoftBank Capital to analyze comments made on social media sites, including Twitter, about television programming, a growing trend known as “social TV.”
“This acquisition reflects our commitment to the social TV market,” Ali Rowghani, chief operating officer of Twitter, wrote in a blog post Tuesday evening that confirmed the Bluefin acquisition.
Bluefin Labs not only uses its software to measure how many people are commenting online about a certain show, such as “The Bachelor” or “The Biggest Loser,” and what they are saying, it also sells that information to clients that include television networks such as Fox Broadcasting Co. and brands such as PepsiCo.
Twitter said it would use Bluefin’s technology to further its partnership with the television ratings company Nielsen and to create “ad products and consumer experiences in the exciting intersection of Twitter and TV.”
Much of Bluefin’s social media analysis is already focused on Twitter, which has grown into a sounding board for criticism and commentary about everything from last year’s presidential debates to the Super Bowl.
“While our products have always included data from multiple social media services, the reality is that Twitter is the platform where the overwhelming majority — about 95 percent — of public real-time engagement with TV happens,” said Bluefin executives in a statement about the acquisition.
Last week, Twitter announced the purchase of another Cambridge start-up called Crashlytics, a company founded in 2011 to provide mobile app developers with software to detect bugs in their products. Terms of that deal also were not announced.
Many other big West Coast tech companies have followed a similar pattern, buying up local start-ups and then using the acquisitions to establish local offices.
Recently, PayPal, the payment division of Internet auction house eBay Inc., opened an office in Boston’s Financial District after it bought Where Inc., a mobile technology firm, for $135 million in 2011.
Giant online retailer Amazon.com Inc., which bought North Reading robot maker Kiva Systems for $775 million last year, has opened an office in Cambridge, too.
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