Is this article peer reviewed? Check any paper by DOI, link or title
Paste one DOI, link or title to see what kind of work it is, any retraction, whether a preprint now has a journal version, and where to read it free. No index can certify peer review, so we show what the records say, who says it, and how to confirm it.
Check a paper
Free, no sign-up. No AI model is involved, and nothing you paste is saved.
Checking a whole reference list? Use the Reference Checker.
Writing from your sources? Upload the PDFs you have and ask what they say. It only cites papers in your library, and every citation opens the passage it came from.
Try it with your papersWhat your result means
Each line in the result comes from a public record and says whose record it is. This is what each kind of result can and cannot tell you.
| What the record shows | What it says about peer review | What to do |
|---|---|---|
| Journal article | Where it was published. No index records how this article was reviewed. | Read the journal's review policy, or look the journal up in Ulrichsweb through your library. |
| Review article | It depends on the journal: Nature Communications says its “Reviews are always peer reviewed to ensure factual accuracy, appropriate citations and scholarly balance”. Source | Check whether your brief wants the primary studies it summarises. |
| Editorial, letter or book review | National University Library says these are “usually not reviewed”, even in journals that review research articles, and UQ Library warns that not all articles in peer-reviewed journals are refereed. National University Library; UQ Library | Treat it as commentary, not as evidence. |
| Preprint | Shared before journal peer review: “not yet certified by peer review” (NLM). Source | Look for the published version and cite that where you can. |
| Conference paper | It depends on the conference. | Check the call for papers or the proceedings' preface. |
| Book or chapter | Peer review of books is “a less codified practice than that of journal articles or conference papers”. Source | Check the publisher's page for the book or its series. |
| Thesis or dissertation | “Theses and dissertations are not peer-reviewed” (University of Plymouth Library). Source | Look for articles the author published from it. |
| Report or working paper | Issued outside the journal system. | Appraise it as grey literature. |
| Peer review report | A reviewer's comments on another work. | Follow the link to the work it reviews. |
| Retracted | Its “findings and conclusions cannot be relied upon” (COPE). Source | Cite it only to discuss it, and say that it was retracted. |
| Expression of concern | Not a retraction: “major and credible concerns about the reliability of a publication which do not meet the criteria for a retraction” (COPE). Source | Read the notice before you rely on it. |
| Correction | Not a retraction. | Check that the correction does not change the part you cite. |
| Listed in DOAJ | DOAJ requires peer review of the journals it lists. Source | A rule for the journal, not a record for this article. |
Does a DOI mean an article is peer reviewed?
No. A DOI shows that something was registered and published, not how it was checked. Crossref, which registers DOIs for its member publishers, says “A DOI itself is therefore not a mark of quality or endorsement”. Preprints, theses, datasets and editorials get DOIs too: on 4 October 2026 Crossref held about 4.1 million posted-content records, the type it uses for preprints, and 842,106 of them linked to a later published version. arXiv's DOIs are registered with DataCite instead. So the checker reads what kind of work the DOI's record describes, rather than treating any DOI as a sign of review.
How to check if an article is peer reviewed
- Find out what kind of work it is. Paste it into the checker above: if it is an editorial, a letter or a preprint, that answers most of the question before you look at the journal.
- Look the journal up in Ulrichsweb through your library's databases. In the University of Queensland Library's words, “A refereed icon appears next to the journal title if it is peer-reviewed.”
- If the journal is not in Ulrichsweb, go to its website and read the author guidelines, instructions for authors or About pages for its review process, as UQ Library suggests.
- For an open access journal, check DOAJ, which requires that “All articles must pass through a quality control system (peer review) before publication.”
- Use your library search's peer-reviewed filter, if it has one.
One caveat applies to every step. UQ Library warns that “not all articles in peer-reviewed journals are refereed or peer-reviewed, for example, editorials and book reviews.”
Found it on Google Scholar, PubMed or ResearchGate?
Where you found a paper does not decide whether it was reviewed. Google Scholar searches “articles, theses, books, abstracts and court opinions, from academic publishers, professional societies, online repositories, universities and other web sites”. PubMed includes preprints, and its help pages describe a filter for them: “The Exclude preprints filter will exclude preprint citations from your search results.” A PDF on a sharing site or in a repository can be any version, from a first draft to the published article. So paste the DOI, the link or the title here: the checker goes by the record behind it, and says when the free copy sits in a repository.
Is a preprint peer reviewed, and has it been published since?
A preprint is shared before journal peer review. The US National Library of Medicine describes preprints as “complete and public drafts of scientific documents, not yet certified by peer review.” The servers say so themselves: bioRxiv and medRxiv state that “Articles are not peer-reviewed, edited, or typeset before being posted online.”, and arXiv that “Material is not peer-reviewed by arXiv”. APA Style adds that preprint versions “may or may not be peer reviewed or may be the author’s final, peer-reviewed manuscript as accepted for publication.”
Many preprints are published in a journal later, and the link between the two versions has to be added: no index finds every one by itself. Crossref asks preprint servers to “Link your posted content record to that other record within seven days of receiving an alert.” bioRxiv “will usually automatically add a link to the published version within several weeks of journal publication.”, and notes that “On occasion a match is not made because the title or authors have changed”. When we checked 8 bioRxiv preprints whose journal versions came out on 1 and 2 June 2025, 2 carried the link only on the journal's record. So the checker looks both ways: the preprint's own record, the journal records that name it as an earlier version, and, for arXiv, the version the authors listed in arXiv's DataCite record.
When it finds a published version, cite that one where you can. APA Style's guidance is “Ideally, use and cite the final, published version of a work.” Our guide to citing preprints in a literature review has the reference formats.
Is it retracted, and can I still cite it?
A retraction or other notice is a separate record with its own DOI, linked to the paper it concerns. Crossref says “In September 2023, we acquired the Retraction Watch database”, which is “updated every working day by Retraction Watch”. Expressions of concern and corrections are included too, but Crossref says “these are not as comprehensive as retractions”. The checker shows each notice with who recorded it, the publisher or Retraction Watch, and its date, and links the notice.
COPE, the Committee on Publication Ethics, describes retraction as alerting readers to articles whose “findings and conclusions cannot be relied upon”, and notes that “Unreliable content or data can result from honest error, naive mistakes, or research or publication misconduct.” If you cite a retracted paper at all, cite it to discuss it and say that it was retracted. An expression of concern is different: COPE says one may be warranted when there are “major and credible concerns about the reliability of a publication which do not meet the criteria for a retraction”. Read the notice before you rely on the paper.
OpenAlex flags retractions too, but a 2024 study found that its single retraction flag misclassified papers, and that “The issue affects data provided by OpenAlex in the period between 22 Dec 2023 and 19 Mar 2024” (Hauschke and Nazarovets). So Crossref is the authority here, and a flag that only OpenAlex raises is shown as OpenAlex's.
Our guide to checking retractions covers what to do when you find one in your draft. Checking a whole reference list? The Reference Checker flags retractions for up to 30 references at a time.
Is this journal peer reviewed?
Paste the journal's ISSN (for example 1549-1676), or the DOI of any article from it. You will see whether DOAJ, the Directory of Open Access Journals, lists the journal, the review process the journal declared to DOAJ, and its website.
DOAJ's criteria are strict: “All articles must pass through a quality control system (peer review) before publication.”, and “At least two independent reviewers must review each article, with an exception for arts & humanities journals (for which editorial review must be handled with a minimum of two editors)”. But “DOAJ only accepts open access journals”, so a subscription journal's absence from DOAJ says nothing about its review. For those, read the journal's author guidelines or look it up in Ulrichsweb through your library.
The checker never labels a journal fake or predatory. It shows what the listings say and where the journal's own policy is written.
Where to read it free
The checker uses OpenAlex's definition of open access: “a work is OA if there’s a URL where you can read its full text without paying money or logging in”. The free copy is not always the published version. A copy in a repository may be the accepted manuscript or an earlier draft, so the result says where the copy is held. Check it matches the published article before you quote page numbers or figures.
When the paper has an open-access PDF, one press adds it to a free Litrevu library, where you can ask questions about it. It only cites papers in your library, and every citation opens the passage it came from. A retracted or flagged paper is never offered.
How the checker works, and its limits
Where each answer comes from
- Crossref: what kind of work a DOI's record describes, links between preprints and published versions, notices including the Retraction Watch database, and statements publishers deposit about review.
- OpenAlex: its classification of the work (such as editorial or letter), the journal's DOAJ flag, free copies and PubMed IDs.
- DOAJ: the review process an open access journal declared. DOAJ says “The journal-level metadata is available with a CC0 waiver”.
- DataCite: arXiv records, including the published version the authors listed.
- doi.org: whether a DOI is registered at all.
Tested by hand
Every change to the checker runs against 24 lookups whose right answer we checked by hand, including a retracted paper, an expression of concern, preprints linked to their journal versions in both directions, an arXiv preprint, a conference paper, a book chapter, an editorial, a letter, a thesis and journals listed in DOAJ.
Limits
- Answers from the indexes are kept for up to 24 hours, and the indexes themselves can lag behind a notice on the publisher's site.
- Crossref's coverage of expressions of concern and corrections is thinner than its coverage of retractions, and OpenAlex does not record expressions of concern at all.
- Kinds of work are as the publisher registered them or as OpenAlex classifies them, and either can be wrong.
- Links from preprints to published versions are often missing, so a missing link never means the preprint was not published.
- Crossref says “Crossmark is not currently supported for posted content.”, so a withdrawn preprint may not show as withdrawn.
- Books, chapters, theses, reports and some regional journals are often missing from these indexes.
- It does not judge a paper's quality, and it never calls anything fake or predatory.
- No AI model is involved, and nothing you paste is saved.
Sources, checked on 4 October 2026
- Crossref: Share your feedback on the new Crossref member practices (10 August 2026), checked 4 October 2026.
- OpenAlex Help Center: Work types, checked 4 October 2026.
- US National Library of Medicine: NIH Preprint Pilot (PubMed Central), checked 4 October 2026.
- About bioRxiv, checked 4 October 2026.
- About medRxiv, checked 4 October 2026.
- About arXiv, checked 4 October 2026.
- SSRN Support Center: Welcome to SSRN, Elsevier’s Preprint Server, checked 4 October 2026.
- APA Style: Preprint article references, checked 4 October 2026, read from the Internet Archive copy of 25 August 2026.
- APA Style blog: How to cite unpublished works, checked 4 October 2026, read from the Internet Archive copy of 14 September 2026.
- DOAJ: Guide to applying, checked 4 October 2026.
- DOAJ: Terms and conditions, checked 4 October 2026.
- University of Queensland Library: Check if it’s peer-reviewed, checked 4 October 2026.
- National University Library: How do I know if the article I found is peer reviewed?, checked 4 October 2026.
- National University Library: Are conference papers peer reviewed?, checked 4 October 2026.
- IEEE Conferences, Events and Experiences: Managing peer review and using tools, checked 4 October 2026.
- Nature Communications: Commissioned content, checked 4 October 2026.
- University of Plymouth Library: Theses (updated 21 July 2026), checked 4 October 2026.
- Hammarfelt, Hammar and Francke (2021): Ensuring quality and status: peer review practices in Kriterium, a portal for quality-marked monographs and edited volumes in Swedish SSH. Frontiers in Research Metrics and Analytics, checked 4 October 2026.
- Cochrane Handbook for Systematic Reviews of Interventions, chapter 4: Searching for and selecting studies, checked 4 October 2026.
- Crossref documentation: Retraction Watch, checked 4 October 2026.
- Crossref documentation: Introduction to posted content (includes preprints), checked 4 October 2026.
- COPE: Retraction guidelines (last reviewed 29 August 2025), checked 4 October 2026, read from the Internet Archive copy of 30 March 2026.
- COPE: Expressions of concern (last reviewed 27 August 2025), checked 4 October 2026, read from the Internet Archive copy of 22 April 2026.
- OpenAlex Help Center: Open access, checked 4 October 2026.
- About Google Scholar, checked 4 October 2026.
- PubMed User Guide, checked 4 October 2026.
- Hauschke and Nazarovets: (Non-)retracted academic papers in OpenAlex (arXiv:2403.13339), checked 4 October 2026.
Questions
Can this tool tell me for certain that an article was peer reviewed?
No, and no tool that reads publication records can. Crossref says “A DOI itself is therefore not a mark of quality or endorsement” and that it does not “assess the quality of our members’ outputs or the integrity of the research process”. OpenAlex says of its work types: “We don’t decide the boundary between types; we standardize the label.” So the checker reports what the records show (the kind of work, where it appeared, notices, versions and the journal's DOAJ listing), says who made each statement, and links the journal's policy so you can confirm it.
Does a DOI mean an article is peer reviewed?
No. Preprints, theses, datasets and editorials get DOIs too: on 4 October 2026 Crossref held about 4.1 million posted-content records, the type it uses for preprints. Paste the DOI above to see what kind of work it points to.
Is a preprint peer reviewed? Is it considered published?
A preprint is shared before formal peer review: NLM calls preprints “not yet certified by peer review”. APA Style says a preprint “is usually an informally published scientific or scholarly work” and that “preprints are not treated as unpublished works” in a reference list. SSRN says papers posted there “are not considered ‘published’ or the final version”. Cite the journal version if one exists. Our guide to citing preprints covers the formats.
Are arXiv, bioRxiv, medRxiv and SSRN papers peer reviewed?
Not by the server that posts them. arXiv says “Material is not peer-reviewed by arXiv”. bioRxiv and medRxiv each say “Articles are not peer-reviewed, edited, or typeset before being posted online.” SSRN's support page says a preprint “has not been validated by the critical process of peer review”. medRxiv adds that preprints “should not be relied on to guide clinical practice or health-related behavior”. Many are published in journals later: paste the DOI or link above to see whether a published version is linked.
How do I check whether a preprint has been published in a journal?
Paste it above. The checker reads the preprint's own Crossref record, then the journal records in Crossref that name it as an earlier version, which finds links the preprint's record is missing, and, for arXiv, the version the authors listed in arXiv's DataCite record. If none of these has a link, search the title and first author in Google Scholar: bioRxiv notes that a match is sometimes missed “because the title or authors have changed”.
Is a preprint grey literature?
Many reviews treat it that way. The Cochrane Handbook uses grey literature for “reports published outside of traditional commercial publishing”, and says preprints, “versions of scientific articles that precede formal peer review and publication in a journal”, can be “a potentially relevant source of study evidence”. If your review protocol says how to handle preprints, follow it. Our grey literature guide covers searching for and appraising them.
Are editorials, letters and book reviews peer reviewed?
Usually not, even in a peer-reviewed journal. The University of Queensland Library warns that “not all articles in peer-reviewed journals are refereed or peer-reviewed, for example, editorials and book reviews.”, and National University Library says “Items like editorial letters, news pieces, and book reviews are usually not reviewed”. The checker labels these when OpenAlex classifies a record that way, and says the label is OpenAlex's, because publishers often register them as ordinary journal articles.
Is a review article peer reviewed?
It depends on the journal's policy. Nature Communications, for example, says “Reviews are always peer reviewed to ensure factual accuracy, appropriate citations and scholarly balance”, while “Comments are not typically peer reviewed.” A review article summarises other studies, so check whether your brief accepts it as evidence or wants the primary studies it cites.
Is a conference paper peer reviewed?
It depends on the conference. National University Library notes that “Generally speaking, papers presented at conferences are working papers; they are not peer-reviewed journal articles.” Some organisers review every paper: IEEE says “Submissions to IEEE conferences all undergo a review process by independent referees who are knowledgeable in the pertinent subject area.” Check the conference's call for papers or the preface of the proceedings.
Is a thesis or dissertation peer reviewed?
Not in the journal sense. The University of Plymouth Library puts it plainly: “Theses and dissertations are not peer-reviewed”, though it adds that a PhD thesis will have passed a defence before a panel of academics. It recommends “seeing if the author has published any articles from it”, and the checker suggests the same.
Is a book chapter peer reviewed?
Sometimes, and it is harder to tell than for an article. A 2021 study notes that “the peer review of books is a less codified practice than that of journal articles or conference papers, and the processes and actors involved are far from uniform” (Hammarfelt, Hammar and Francke, Frontiers in Research Metrics and Analytics). Look at the publisher's page for the book or its series.
Is everything on Google Scholar or PubMed peer reviewed?
No. Google Scholar searches “articles, theses, books, abstracts and court opinions, from academic publishers, professional societies, online repositories, universities and other web sites”. PubMed includes preprints, and its help describes a filter that removes them. Where you found a paper does not decide whether it was reviewed, so paste its DOI or title here to see its record.
How do I check whether a journal is peer reviewed?
Paste its ISSN, or the DOI of any article from it. You will see whether DOAJ lists the journal and the review process the journal declared there. DOAJ lists only open access journals, so for a subscription journal read its author guidelines or look it up in Ulrichsweb through your library, where, in the University of Queensland Library's words, “A refereed icon appears next to the journal title if it is peer-reviewed.”
Can I cite a retracted paper, and what is an expression of concern?
If you cite a retracted paper at all, cite it to discuss it and say that it was retracted: COPE describes retracted articles as ones whose “findings and conclusions cannot be relied upon”. An expression of concern is not a retraction. COPE says one may be warranted when there are “major and credible concerns about the reliability of a publication which do not meet the criteria for a retraction”, so read the notice and decide how much weight the paper can bear. Our guide to retracted papers covers what to do when you find one in your draft. To check a whole reference list at once, use the Reference Checker.
Why does it say no published version is linked when I know there is one?
The links come from preprint servers and publishers, and they are often missing: on 4 October 2026, 842,106 of Crossref's posted-content records carried one, about one in five. Search the title and first author in Google Scholar. If you find the published version, paste its DOI here to check that version too.
Why could it not find my paper?
Books, chapters, theses, reports and some regional journals are often missing from Crossref and OpenAlex, so check your library catalogue or Google Scholar. If you pasted a publisher link, it may not contain the DOI: paste the DOI or the title instead.
Is it free, and do you keep what I paste?
Free, with no account, and with an hourly limit per visitor. What you paste is looked up in Crossref, OpenAlex, doi.org and, when needed, DOAJ and DataCite, and the answer comes back to you. No AI model is involved, and nothing you paste is saved. The indexes' answers are kept in memory for up to 24 hours, so a popular paper is not fetched again for every student.
Related guides
- Can you cite a preprint in a literature review?
- How to check whether a paper you cited has been retracted
- How to find and use grey literature in a literature review
- How to find academic sources for your research paper
- How to critically appraise a research paper
- How recent do sources need to be in a literature review?
- How to update an existing literature review
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