A week after the presidential election, the fight against fake news is finally ramping up.

A new browser extension will warn readers when they arrive at a website known to produce fake news or hoaxes. The pop-up or banner alerts readers that "the information on this site might be false or misleading."

The site Breitbart, with a warning imposed by the Fake News Alert extension. Image: screenshot/breitbart

The "Fake News Alert" Chrome extension, created by New York magazine journalist Brian Feldman, joins the B.S. Detector Chrome extension launched Tuesday that identifies hoax news articles on Facebook.

Both extensions rely on a manual list of sites likely to contain false information presented as news.

Fake News Alert uses a list of misleading websites compiled by a media studies professor. The list includes hoax sites like Breitbart and InfoWars as well as satirical sites like ClickHole that could confuse some readers.

The fight against fake news has gained steam after Facebook CEO Mark Zuckerberg denied that hoaxes on Facebook could have had any impact on the U.S. presidential election.

Over the past week, Facebook and Google have both taken steps to crack down on hoaxes by limiting the sites' use of their ad networks. But neither company has made a definitive effort to eliminate fake news entirely.

Download the new crop of browser extensions for everyone you know, to check hoaxes on Facebook and the rest of the internet.

Everyone put this on your parents' computers over the holidays. https://t.co/KkbHIi6oiP — Nicolas Gonzalez (@NicoSGonzalez) November 16, 2016