AI Tools for Reviewing a Paper, Compared by What Each One Actually Does

Your manuscript is finished, the journal is chosen, and you have four tabs open with four different prices. The question you are trying to answer, which of these stops me getting rejected, has a trap built into it: it assumes they compete with each other, and mostly they do not. Before you pay for any of them it is worth knowing what each one looks at and, above all, what none of them looks at, because the reason a Q1 editor returns a paper without sending it out for review is usually not the English alone.

They all say they review your paper. None of them reviews the same thing

Reviewing a manuscript is at least five separate jobs, and no tool on the market does all five. There is language: grammar, academic register, sentences a native speaker would not write. There is format: required sections, word counts, whatever that particular journal's author guidelines demand. There is integrity: plagiarism, generated text, retouched figures. There are references: that they exist, that they have not been retracted, that they say what you claim they say. And there are the numbers: that the p value you report is the one your degrees of freedom produce, that the effect size is consistent with the F on its own line, that the N in your Method matches the N in Table 2.

Compared on price, all five look like alternatives and you have to pick one. Compared by category, four of them turn out to be complementary and the fifth, ChatGPT, is a different animal altogether that is frightening and useful in roughly equal measure. What follows is what each one covers according to its own website, not according to mine.

Everything you read here about Paperpal, Writefull, Scribbr, Grammarly and ChatGPT was checked on their official pages on 4 September 2026. If a claim was not written on their own site, it is not in this article, and where I could not read a price I say so rather than filling the gap. Prices move every few months and you will see them change; the split by category is far more stable, and it is the part that should actually decide your purchase.

Paperpal: the widest coverage, and the only one of the five that looks at your bibliography

Paperpal belongs to Cactus Communications and organizes its catalog into three blocks that tell you a lot about its approach: write and improve, search and cite, check and finalize. The first holds a writing assistant, a paraphraser, sentence rewriting and translation. The third holds a grammar checker, an AI proofreader, a plagiarism checker, an AI detector, the reference checker and a submission readiness checker. It works inside Word, Google Docs, Overleaf, Chrome and the browser, which for a real writing workflow matters more than any single feature on that list.

The Reference Checker is the piece that separates it from the rest and deserves detail, because it is as close as the language market gets to touching content. Its own page advertises nine checks and spells out six: it flags retracted references, identifies AI-generated references, detects dead links and invalid DOIs, points out journals of doubtful quality, assesses whether a citation genuinely supports the sentence it accompanies, and cross-matches in-text citations against the reference list. It does this against an in-house corpus they advertise at more than 250 million articles, updated daily. That page does not name Crossref or PubMed: it talks about a verified corpus, and that is all I can tell you without making something up.

The Reference Checker sits in their paid tier, Prime, capped at 10,000 words a month with pay-per-use above that; their own blog puts Prime from 25 US dollars a month, checked on 4 September 2026. Separately there is Preflight, their modular screening platform for publishers, universities and research teams: seven modules, of which the screening one covers metadata, figures, tables, legends, disclosures, references, structure and counts, another deals only with duplicated, manipulated or AI-generated images, and another returns a reviewer-style assessment.

What appears on neither of those two lists, not the tool's and not Preflight's, is p values, effect sizes and degrees of freedom. Paperpal does one job very well that almost nobody else does, the bibliography, and makes no claim to do the other. If your specific fear is a mis-copied reference or a retraction that slipped through, read how to check your references before submitting first and decide whether that is enough for you.

Writefull: the most surgical with academic English

Writefull does one thing and does it with noticeable precision: correcting the English of a scientific text with models trained on journal articles. The difference from a general-purpose corrector is vocabulary and register, and if you write in English without being a native speaker it is probably the tool on this list that changes your manuscript most for what it costs.

It ships widgets with names of their own: Academizer, which lifts a colloquial sentence into academic register; a paraphraser; a title generator that works from your abstract; an abstract generator that works from your full paper; and TeXGPT, which writes the LaTeX for tables, formulas and equations. That last detail weighs more than it looks: Writefull lives inside Overleaf, and if your manuscript is in LaTeX it is the only one of the five that does not make you leave the document to correct it.

There is a nuance about Writefull Cite worth understanding properly, because the name misleads. It does not verify your references: it screens your text for statements that should be backed by a reference and carry no citation, and flags them so you do not plagiarize by accident. That is the opposite problem to the one Paperpal's Reference Checker solves, and both are useful for different reasons. One caveat: their own page says Cite is available to institutions only. Writefull Revise, by contrast, is for the author: you upload the document, see the overall language quality and get it back corrected with tracked changes.

Prices come from their own plans panel, which loads them dynamically, and on 4 September 2026 I could not read a figure there I would be willing to quote you; so I am not quoting one, and you check before you pay. What can be read end to end is their catalog of products and widgets, and there is not a single item on that list that mentions statistics or verifying a bibliography against databases. It is not an oversight: it is not what they sell, and they do not pretend otherwise.

Scribbr: people, which is why the limit sits somewhere else

Scribbr's editing service is not an AI reading your manuscript, it is a human editor. They advertise more than 800 editors, all put through an in-house academy with a 2% pass rate, and they assign you one based on your field of study and document type. You get the file back with tracked changes and a personal letter from your editor, and the service's own front page advertises turnaround from 12 hours. Alongside the human service they also sell standalone automated tools: a plagiarism checker, an AI proofreader, a text humaniser.

The standard service catches spelling, grammar, inconsistencies in dialect, overuse of the passive and subjective or inflated language. On top of that you can buy four add-ons: a structure check, a clarity check, document formatting and citation editing. That last one deserves the same warning as Writefull Cite: citation editing is done by a human expert who applies your style guide consistently, checks the reference list and flags entries that look incomplete, and their own small print says the expert will not create the citations for you or go hunting for missing details. Consistency is not existence.

Their own strapline is a language expert improving your writing, and it is an exact description of what you are buying. A human language editor is not going to recompute your ANOVA or ask whether your Cohen's d is consistent with your t, and should not: it is neither their specialty nor what they are selling you. Price depends on word count, turnaround and academic level and comes out of a calculator on their site, so I am not going to quote you a figure here that would depend on your document rather than theirs.

Grammarly: not built for a paper, and it does not pretend to be

Grammarly is the best known of the five and the one with least to do with what is in front of you. Its declared catalog is general writing: rewriting, proofreading, paraphrasing, simulated reader reactions, a résumé builder. Among its agents there is a citation finder that locates sources to back your claims and generates the citation for you, and a separate citation generator; neither of them verifies an existing bibliography against bibliographic databases.

The plans, checked on its pricing page on 4 September 2026: free at €0, Pro at €12 a month and an enterprise tier on request. The free plan covers spelling and grammar, the tone of your text, and a hundred AI prompts. The plagiarism checker, the AI detector and the humaniser for generated text sit in the paid tiers; that a humaniser exists at all says more about its target audience than anything I could write here.

For a psychology or health sciences manuscript it is the most distant of the five, and fairness requires saying it never promised to be close. If you write emails, reports and occasionally a paper, it is a perfectly sensible purchase. If what you have in front of you is a Q1 submission, Paperpal and Writefull will read your academic register considerably better.

ChatGPT: the only one that can touch your data, and the only one whose maker warns that it invents references

ChatGPT is the exception on this list for two opposite reasons. The first is in its favor: it is the only one of the five that can run code over a file you upload. Its own help center documents this plainly: for data analysis tasks, ChatGPT writes and runs Python in a Jupyter-style environment to run calculations, analyze data and generate charts. And that is true. If you upload your dataset and ask it to run the analysis in Python, a machine is doing the arithmetic, not a model predicting what arithmetic sounds like.

The second reason is on another page of that same help center, the one asking whether ChatGPT tells the truth, and it is among the more honest things a company has written about its own product: among its typical inaccurate outputs they explicitly list fabricated quotes, studies and citations or references to sources that do not exist, and they recommend using it as a first draft rather than a final source, verifying quotes, data and references to external documents. Their words, checked on 4 September 2026, not a competitor's.

For your manuscript the risk has a very recognisable shape. You paste in your results table, ask whether the p values are consistent with the degrees of freedom, and get back a confident, well-written paragraph. Looking at that answer you have no way of knowing whether it executed code or predicted the prose that usually accompanies that question, and the two answers look remarkably alike. If you are going to use it this way, force it to write and run the code, then read the code. This is worked through in what ChatGPT can and cannot do with the statistics in your thesis.

The comparison, by category rather than by who is best

Lined up by what each one does, as of 4 September 2026, the table looks like this. You will see straight away that no column wins outright: some categories have three candidates and one has none.

Language and academic register. Paperpal and Writefull, both specialized in scientific text. Scribbr, with people. Grammarly, in a general-purpose version. ChatGPT, with no declared academic specialization. This is the category with the most supply and the lowest price per unit of help.

Format and journal fit. Paperpal, through its submission readiness checker and Preflight. Scribbr, as a paid add-on on top of the base service. The other three do not compete here.

Integrity: plagiarism, generated text, images. Paperpal, Scribbr and Grammarly all sell a plagiarism checker. Paperpal and Grammarly add AI-text detection. Only Preflight, Paperpal's screening platform, looks at duplicated or manipulated figures. Writefull does not enter this category.

References you have already written: that they exist, that they are not retracted. Paperpal, and nobody else among the five. It is the least expected finding in this whole comparison, and the reason Paperpal stops being interchangeable with any other proofreader.

Citations that are missing. Writefull Cite, and nobody else, though only if your institution holds a license. It is the inverse problem, it is also real, and a reviewer can also flag it at you.

Statistics already written, recomputed. None of the five. Not Paperpal, not Writefull, not Scribbr, not Grammarly. ChatGPT can analyze your raw data if you force it to run code, which is a different and genuinely valuable thing, but it does not recompute the numbers already sitting in your manuscript unless you build that yourself.

That last empty cell has a property that makes it easy to automate well: a p value is not an opinion, it is a deterministic function of the test statistic and its degrees of freedom. If you report t(118) = 2.31 and p < .001, that is not debatable, it is recomputable, and it comes out at p = .023. The same goes for an effect size that does not match the F on its own line. That is exactly what the AI paper reviewer does, with code rather than a model, and what it also does with references, verifying each one against eight databases: Crossref, OpenAlex, Semantic Scholar, PubMed, DOAJ, arXiv and OpenLibrary. Before you upload anything you can read a full sample report and see whether that is what you are missing.

Frequently asked questions

If I can only pay for one, which should I buy?

It depends on where you are being rejected, not on which is best. If the comments you get are about clarity, English or a text that is hard to follow, Writefull if you write in LaTeX and Paperpal if you write in Word, or Scribbr if you would rather have a person and can afford one. If your worry is the bibliography, Paperpal is the only one of the five that verifies it. If the comments are about analyses, assumptions or results that do not add up, none of the five is looking at that.

Do Paperpal and Writefull compete with each other?

On language, yes, and there the choice is more about workflow than quality. Writefull lives inside Overleaf and Word and is very fine-grained about academic register; Paperpal covers more ground, across Word, Google Docs, Overleaf and the browser, and adds the integrity and reference layer Writefull does not have. If you write in LaTeX, Writefull. If you also want somebody looking at your bibliography, Paperpal. Owning both is not absurd: they do not fully overlap.

Can I use ChatGPT to check my analyses?

Yes, on one condition: that you force it to write and execute the code, and that you read the code. Its data analysis tool genuinely calculates, and there the result is as good as the code it wrote. What you cannot do is paste in a table and ask whether the numbers add up, because it will answer with convincing prose without having done the arithmetic and you will not be able to tell the two cases apart. OpenAI itself recommends treating its output as a first draft and verifying quotes, data and references.

Does any of them verify that my references genuinely exist?

Of these five, only Paperpal, through its Reference Checker, against an in-house corpus they advertise at more than 250 million articles, checking retractions, broken DOIs and AI-generated references. Writefull Cite does the opposite, detecting sentences with no citation. Scribbr and Grammarly check formatting and style consistency, which is not the same as existence. And ChatGPT is precisely the tool that can fabricate the reference somebody would then have to verify.

Does any of these replace peer review?

None of them, and that includes ours. They are all different ways of looking at your manuscript before somebody who can reject it looks at it, which in the case of an automated tool means author self-assessment of the author's own work. The difference from peer review is not one of power but of kind: a reviewer decides whether your contribution deserves publishing, and no program decides that. There is more detail in what an AI paper reviewer actually is.

Do I have to declare to the journal that I used one of these?

Check your journal's instructions for authors before you submit, because policies vary and change quickly. The distinction that usually matters is between language assistance applied to text you already wrote and generation of new content, and not every tool on this list falls on the same side of it. An English proofreader and a model that writes your discussion are not the same declaration, even though both get called AI.

None of the six tools in this comparison, ours included, is peer review: they are different ways of looking at your manuscript before someone who can sink it looks at it. And if what you are missing is not a check but a decision, which model to fit or how to defend an analysis a reviewer is arguing with, that takes a person: that is what the consulting is for.