Predatory journals are publications that charge authors a fee while failing to provide the genuine peer review, editorial oversight, and long-term archiving that legitimate journals deliver. They exploit the open-access publishing model, in which authors pay an article processing charge, by collecting that fee and publishing almost anything with little or no scrutiny. For researchers, the danger is real and lasting: a paper in a predatory journal can undermine an otherwise strong CV, and it is very hard to undo once published.
This guide explains the warning signs of predatory publishing, the checklists that reliably separate genuine journals from fakes, and the contested cases, such as MDPI and Frontiers, that do not fit neatly into either category.
Legitimate open-access journals charge an article processing charge to cover editorial and hosting costs, and in return they run real peer review, maintain an editorial board, and preserve the published record. Predatory journals mimic the surface of this model while skipping the substance. They send mass email invitations, promise acceptance within days, and publish on payment. The result is a venue that looks like a journal and issues something that looks like a publication, but carries none of the quality signals that make a publication count.
The harm is not only reputational. Work published in a predatory venue is rarely indexed, so it is hard to find and almost never cited. It cannot be resubmitted to a legitimate journal without a formal retraction, because it has technically already been published. And reviewers and hiring committees increasingly scan CVs for predatory titles as a marker of poor judgement.
Most predatory journals share a recognisable set of red flags:
- Guaranteed or extremely fast acceptance. A promise to publish within days is incompatible with real peer review.
- Unsolicited spam invitations, often with flattering but generic language and odd English.
- Fake or misleading metrics. Invented "impact factors" with names that imitate the real Journal Impact Factor. Our explainer on the journal impact factor covers how the genuine metric works and how to spot fabricated ones.
- Unverifiable editorial board. Named editors who did not agree to serve, or who do not exist.
- Hidden or surprise fees, disclosed only after acceptance.
- No clear archiving or indexing, despite claims to the contrary.
- A scope that is impossibly broad, covering unrelated fields in a single title.
No single sign is conclusive, but several together are decisive.
Vetting a journal takes a few minutes and is far easier than escaping a bad decision later. Run these checks:
- Directory of Open Access Journals (DOAJ). Legitimate open-access journals are usually listed. Absence is not proof of fraud, but presence is a strong positive signal.
- Indexing. If the journal claims indexing in PubMed, Web of Science, or Scopus, verify it directly in those databases rather than trusting the journal's website.
- Beall's List successors. The original Beall's List of predatory publishers stopped updating in 2017, but archived versions and community-maintained successors remain useful reference points.
- Think Check Submit. This neutral checklist walks you through verifying a journal's legitimacy and is widely endorsed.
- The editorial board. Look up two or three named editors and confirm they are real researchers who acknowledge the role.
Our broader guide to choosing a target journal folds these checks into the wider decision of where to submit, alongside scope, audience, and turnaround.
The Contested Cases: MDPI and Frontiers
Not every fast or high-volume publisher is predatory, and this is where judgement matters. MDPI and Frontiers are frequently debated. Both publish large numbers of indexed, legitimately peer-reviewed articles, and many researchers publish in them without issue. Critics, however, point to very short review times, heavy reliance on special issues, and aggressive solicitation. The reasonable position is to judge the specific journal, not the publisher as a whole: check the individual title's indexing, editorial board, and recent content, and decide whether it fits your field's expectations. Labelling an entire large publisher as predatory is usually too blunt; ignoring legitimate concerns is too credulous.
If a journal sits in a grey area, the safest move is to choose a clearly reputable alternative. The cost of publishing in a questionable venue, lost visibility, a CV liability, and an article you cannot move, far outweighs the delay of selecting a better home for your work. For high-stakes manuscripts such as a end-to-end systematic review help or a clinical study, having an experienced editor vet the target journal and prepare the submission removes the guesswork. Our expert manuscript editing help and expert medical writing help teams routinely advise on journal legitimacy as part of preparing a paper for submission, and our guide to responding to peer reviewers covers what genuine review should look like once you are in the right venue.
Predatory publishing thrives on haste and flattery. A few minutes of verification, using the DOAJ, real indexing databases, and the Think Check Submit checklist, protects years of work.