The Snopes.com web site was founded by David Mikkelson, a project begun in 1994 as an expression of his interest in researching urban legends that has since grown into the oldest and largest fact-checking site on the Internet — one widely regarded by journalists, folklorists, and laypersons alike as one of the world’s essential resources.
Snopes.com is routinely included in annual “Best of the Web” lists and has been the recipient of two Webby awards.
PolitiFact is a fact-checking website that rates the accuracy of claims by elected officials and others who speak up in American politics.
PolitiFact is run by editors and reporters at The Poynter Institute, a 501(c)(3) nonprofit school for journalists based in St. Petersburg, Fla.
The PolitiFact state sites are run by news organizations that have partnered with the Times. The state sites and PunditFact follow the same principles as the national site.
Link: Politifact and Politifact Global News