Free Citation Extractor — DOI, arXiv, PMID, ISBN, URL

Citation Extractor scans arbitrary text for the persistent identifiers researchers actually use — DOIs (10.xxxx/…), arXiv preprint IDs, PubMed IDs, ISBNs, and plain URLs — and returns a deduped, clickable list. It is the kind of thing you reach for after pasting in a messy references section, an email full of links, or the text layer from a PDF, when you just want every citable identifier on one screen.

Each identifier type has a regular expression tuned to its canonical format. DOIs match the 10.xxxx/… prefix. arXiv IDs match the modern YYMM.NNNNN format with optional version suffix. PMIDs require the PMID: prefix to avoid catching random digits. ISBNs match the 10- or 13-digit format with optional separators. URLs match http(s) schemes. Matches are normalised, deduped, and linked to the canonical resolver for each type.