On the internet, conspiracy theories, propaganda and plain old inaccuracies can stump even the most thoughtful readers, spreading faster than you can say “fake news.”

A small start-up, NewsGuard, says it may have a solution. The effort is led by a pair of veteran news executives — Steven Brill, an author and the founder of the magazine The American Lawyer, and Gordon Crovitz, a former publisher of The Wall Street Journal. On Wednesday the company announced that it had signed Microsoft as its first major client.

NewsGuard has created the equivalent of nutrition labels for news organizations, rating more than 2,000 news and information sites with tags: red for unreliable, green for trustworthy. A team of roughly 50 journalists and analysts is making the evaluations.

NewsGuard has given its stamp of approval to established publications like The New York Times and The Wall Street Journal, as well as later entrants like BuzzFeed and Newsmax. FoxNews.com, The Hill, The Daily Beast and HuffPost have also gotten green lights.