Politifact.org
From the Poynter Institute for Media Studies. With politifact you are able to search claims made in the news or on social media, read the background about the claim, see their ruling and the research the used to come about to that ruling. They also include a source list for further reading. You can also browse by pundits, issues, newsworthy people, political promises and elections, and see Truth-O-Meter results.
FactCheck.org
A project of the Annenberg Public Policy Center. Like Politifact, you can use FactCheck to look up specific claims made in the media. They will give you background on the claim, how they researched it and clarified it, as well as a source list. They also run more specific checks, SciCheck.org and FlackCheck.org, which handles political ads and claims. They also have a Facebook initiative which is working to debunk claims made on Facebook. With FactCheck they cover hot button topics and people.
Snopes
Snopes is an independent publication owned by Snopes Media Group. It began in 1994 investigating urban legends, hoaxes and folklore. As the internet grew, so did the demand for reliable fact checks. With Snopes you can enter claims made in the media and the site will return any research they have done, followed with their findings, background information, how they researched it, and their sources list. If they haven't researched a claim, you can submit it to them to have it researched. They also include original news reporting from Snopes on their site.
Teen Fact Checking Network
From Poynter's MediaWise
Media Bias/Fact Check (MBFC)
You can use this site to check the general overall bias attributed to media outlets by performing a search for the outlet in the search box at the very top of the site. It also identifies questionable sources, ans satire.
WHOXY.com
This site is a lookup for identifying who is behind specific URL addresses.
OpenSecrets.org
Formed by the two leading money-in-politics watchdogs, the Center for Responsive Politics and the National Institute on Money in Politics, Open Secrets reveals where political money comes from and holds political leaders accountable.
International Fact Checking Network's Code of Principles
The International Fact-Checking Network (IFCN) at Poynter was launched in 2015 to bring together the growing community of fact-checkers around the world and advocates of factual information in the global fight against misinformation. Signatories to the code receive training, can attend conferences, and network with each other. They agree to advance accountability in journalism.
You can find the list of signatories here.