Back when I was doing academic publishing I'd use a regex to find all the hyperlinks, then a script (written by a co-worker, thanks again Dan!) to determine if they were working or no.
In the past I've had GPT4 output references with valid DOIs. Problem was the DOIs were for completely different (and unrelated) works. So you'd need to retrieve the canonical title and authors for the DOI and cross check it.
I work on Veracity https://groundedai.company/veracity/ which does citation checking for academic publishers. I see stuff like this all the time in paper submissions. Publishers are inundated
Not all journals require a DOI link for each reference. Most good ones do seem to have a system to verify the reference exists and is complete; I assume there’s some automation to that process but I’d love to hear from journal editorial staff if that’s really the case.
A similar approach should work w/ a DOI.