CiteCheck

Paste a DOI, PMID, or a citation string. CiteCheck confirms the paper exists and is not retracted — it never invents a citation.

Try 10.1016/S0140-6736(18)31809-9 (resolves) or 10.9999/does-not-exist-12345 (does not resolve).
CiteCheck verifies that a citation exists and is not retracted. It does not verify that the paper supports any particular claim, and it is not medical advice.