Fact-checking websites provide fact-checking services on a variety of topics, both political and non-political. They typically fact check popular things happening in the news or online trends. Therefore, you won't find a fact check for every source or claim you find online.
This is a good lateral reading strategy to use when you are researching something broad or topical.
Search Tip: If there is a fact check on your topic, you can usually locate it by searching for an article title or the topic paired with the phrase "fact check."
Breitbart News ran a story claiming there was a peer-reviewed study proving all recent global warming fabricated by climatologists. Essentially, the article is promoting the idea that global warming is a hoax and using a peer-reviewed study to give the claim credibility.
To locate a fact check on this story, you would need to do an internet search for the title of the article and the phrase "fact check." You can see a Snopes article showed up as the first result.
The Snopes article debunked this claim. The "evidence" provided by the Breitbart News story was proven to not be a peer-reviewed article. Snopes reports...
"Breitbart here lowers the bar for what passes as both “peer-reviewed” and a “study”. This report, published on a WordPress blog run by co-author Joseph D’Aleo—a meteorologist who did not complete a PhD, but who prominently advertises his honorary doctorate on the document’s cover page—is not published in a scientific journal. … Given the fact that this study is not published in a journal but on a WordPress blog run by one of the co-authors, it is difficult to see how Wolff’s careful and critical reading of the document constitutes a formal peer review."