Is your source retracted?

Papers get withdrawn after you cited them, and nobody sends you a memo. Paste a DOI; we check it against the open literature index, free, right now.

10 free a day. Trust Wiki receipts get this scan nightly, automatically.
Why this matters
Thousands of papers are retracted every year, and articles that cited them almost never get fixed. Our engine refuses to cite retracted work, and re-checks every receipt's sources nightly. This page is that same conscience, offered free.