A free Model Context Protocol server that verifies references against live registries — catching AI-hallucinated citations, DOIs that resolve nowhere, DOIs that point to a different paper than the one cited, retracted papers, and duplicates.
Add it to Claude or ChatGPT with this URL:
https://citation-guard.mahendrakarpranay.workers.dev/mcp
It returns facts from public registries (doi.org · OpenAlex · Crossref), not AI opinion — so you can check them yourself. Up to 15 references per call.