Source Checker — JeffAPierson.com

What this does: it audits an article's sourcing. Every link in the piece is actually fetched to see whether it still works, then each citation is examined for whether it is the original record or a retelling of someone else's work, whether a better source exists, and which factual claims carry no source at all.

Links are fetched live, so a first check takes a couple of minutes on a heavily-cited article. Every check is stored permanently and served instantly after that.
Source Checker · engine v2 · Article Values Graph™