As a general rule, when I receive a request to referee a paper from a journal, I do my best to accept it unless I have a strong reason not to. One possible reason is that the journal in question is predatory or otherwise morally objectionable (emphatically, this does not include rigorous journals which are just not particularly strong). Usually, it's easy enough to tell a predatory journal from a legitimate one, and a moderate amount of googling tends to resolve most remaining cases. However, I've just run into an edge case I find difficult to resolve, and I was hoping that people wiser than me have already done their due diligence and can share the result.

I'm specifically interested in the MDPI journal Mathematics. It definitely seems to be a real journal publishing papers that are not obviously nonsense and include DOIs. For what it's worth, it even seems to be open access. They have a Wikipedia page, which does not outright call the journal predatory, although it has a section on "Evaluation and controversies" which seems to be longer than all the other material combined. The paper which I received seems to correspond quite well with my fields of research, which is usually quite a good sign, but the deadline sounds unreasonably short.

Any advice would be appreciated!

  • 3
    academia.stackexchange.com/questions/192222/… Does this answer your question? Or this academia.stackexchange.com/questions/8959/…
    – Allure
    Oct 25, 2023 at 12:51
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    It does, thank you! And apologies for my poor search abilities :) Oct 25, 2023 at 12:54
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    There's also the question of Is MDPI a reputable Academic Publisher?
    – Anyon
    Oct 25, 2023 at 12:55
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    "the deadline sounds unreasonably short" - it's up to you whether you're willing to do it in that time frame or not. I personally will as a matter of principle not prioritise review jobs just because they come with tighter deadlines than others. Furthermore, one could interpret the tight deadline as an implicit admission that they don't want a quality review as quality takes time. In my view this reflects badly on the journal, but then many journals also non-MDPI do this these days. Oct 25, 2023 at 13:17
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    As a mathematician, I do not consider MDPI to be a serious publisher and would not accept referee requests from them. Their reputation varies field to field, but they are looked at pretty unfavorably in math. Oct 25, 2023 at 13:36

2 Answers 2


This is not really an answer to the question asked, but it provides background. For context I'm currently employed at MDPI.

  • MDPI is not predatory in the traditional sense of the word (i.e. does not conduct peer review and accepts everything). I don't believe there's anyone that seriously disputes this.
  • MDPI is also not predatory in the sense that they'll take your review and hide it. You can expect your review to be shown to the authors and a response solicited. Exception applies if your review is unacceptable, e.g. if it contains personal attacks.
  • MDPI is arguably predatory under an array of other definitions, however. See the answers I wrote to the linked question above for more. (Someday I hope to be able to write even more, but today is not that day.)
  • It is standard procedure to request reviews in 10 days, but note the review invitation says if you need more time, just ask for it. I don't work for Mathematics, but for the journals I handle, standard procedure is to approve requests for up to 2 weeks (more than that and we look for other reviewers, unless we are struggling with that and/or you are an exceptionally appropriate reviewer for the paper and/or the academic editor explicitly requested you as a reviewer).
  • If you're wondering, the idea behind the very-short review time is that, in theory, it does not take two weeks of non-stop work to review a paper. (I'm told the review culture is different in mathematics, but the people who came up with this don't work in mathematics, so they're unaware.) So the short review time is allegedly more of a "Are you free to provide a quick review? If not we'll ask someone else" question.
  • The fact that the paper is within your expertise indicates the editor who sent the invitation did a good job, which makes me a little happier, since we screw this one up a lot (as in, A LOT).
  • If you accept the invitation, you can expect reminders from the journal office once the deadline is approaching. In this case please communicate with them, since non-responsive reviewers who have agreed to review are one of the most frustrating parts of the editor's job.
  • If you accept the invitation, recommend major revision/rejection and the manuscript is revised, then you'll get a revised version review. In this case standard procedure (at least for the journals I handle) is to ask you for a review in 3 days. You can once again request more time, which may or may not be granted depending on how major your comments were. If you need so much time they feel they can't wait anymore, they might ask the academic editor to check the revision instead.
  • If you accept the invitation, and especially if you write a comprehensive review, you can expect to receive more invitations. It can go up to 2 invitations / month, which for many people becomes spam, especially since quite a few invitations will be to out-of-expertise papers or papers that don't look like they're of reviewable quality. The silver lining is that there is no expectation you'll review, and you can always decline (or not respond - although in this case you'll receive reminders about the invitation).
  • Strictly speaking the above can also happen if you decline or don't respond, but it's less probable. Writing a comprehensive review makes MDPI editors notice you.
  • If you accept the invitation, then you can expect to receive a discount voucher of 50-100 CHF that you can use to reduce the APC, if you choose to submit a paper to MDPI journals in the future.

On a personal level I wouldn't do it,* but ultimately, it's up to you.

*This is not a typo.

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    3 days for checking a major revision seems insane to me... If that's the kind of timeline publishers want, they really should consider paying reviewers.
    – Anyon
    Oct 25, 2023 at 13:40
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    @Anyon +1, the timeline makes me uncomfortable and I'm the one sending the invitations. It's like, even if we accept the premise that the short review time is a "are you free to provide a quick review" question, and I am free to write a review right now, I can't possibly predict that I'll be free by the time the manuscript is revised. It would be irresponsible to decline that invitation however (since I've already checked the manuscript once, I can do it a lot quicker than a fresh pair of eyes). At least it's possible to ask for more time.
    – Allure
    Oct 25, 2023 at 13:45
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    The rest of this conversation has been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Academia Meta, or in Academia Chat. Comments continuing discussion may be removed.
    – cag51
    Oct 26, 2023 at 17:58

Personally, I have denylisted MDPI as a publisher I will not review for. They consistently sent me terrible manuscripts to review and ignored the information I provided about my area of expertise.

They are the only publisher on the denylist.

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