AI peer review tools compared (2026): 40 reviewers, editors and chats
Forty AI peer reviewers, language editors, chats and human editing services in one table: price, what is free, languages, verified references, statistics by code, Word output and confidentiality. Read on 17 Sep 2026, with a source on every row.
Here are the forty tools and services you can use today to review a manuscript before sending it to a journal: AI content reviewers, language editors, the general-purpose chats half the department already uses, human editing from the big publishers and the tools sold to journals themselves. One row each, with its price, what it gives away and what it actually does.
I write this, and I am an interested party: Previum is mine and sits in the first row. That is why the table carries no adjectives, only cells. I read every figure on each tool’s own page on 17 September 2026 and a second reader checked it again the same day; where they disagreed, the second reader’s figure is the one here. Prices change, sometimes month to month, so every row links to its source so you can see it with your own eyes before deciding.
And where another tool suits you better than mine, I say so: there is a whole section for that.
Figures read on 17 September 2026
Who is comparing: Víctor Ciudad-Fernández
PhD in Psychology (University of Valencia), statistical consultant. PhD cum laude from the University of Valencia and MSc in Methodology (Complutense University of Madrid). I publish in indexed journals such as Nature Reviews Psychology, the Journal of Behavioral Addictions and the Journal of Psychopathology and Clinical Science, and I review manuscripts for Q1 psychology journals. I build Previum; I also wrote this comparison, under my own name.
The whole table
Forty rows in five blocks. ✓ means it does it; — that it does not, or does not declare it on its website; n/c that I could not check it. When it does it with a caveat, the caveat is what you read. Previum goes first, with what it does not do written the same way as what it does.
AI content reviewers
Previum. Price: Basic free · Professional €12 (one-off payment per manuscript). What is free: The finding that decides, with the quoted sentence and the fix; references against 8 databases; recomputed p values; figures that do not add up. Languages: Report in Spanish, English, Portuguese and French; the manuscript can be in another language. Reviews the content: Two simulated reviewers and a simulated editor (Professional). References verified: 8 databases, already in Basic. Statistics by code: Recomputed p, GRIM, N across sections and APA 7 in Basic; 87 checks in 11 modules in Professional. Word: comments / tracked changes: Yes, every objection in the margin (Professional) / no. Second round: 30 days, included in Professional. Confidentiality: No training on your manuscript and no advertising; authorship seal and processing record by fingerprint; providers named at /en/security. Institutional: From €390/year. source What it does not do today: tracked changes in the Word file, reading figures, API or MCP, chat about the manuscript, AI-generated text detector.
Reviewer3. Price: $11 per review · $19/month with unlimited reviews (one-off or subscription). What is free: The first findings card and the reference check; the rest is blurred. Languages: English (no others declared). Reviews the content: yes. References verified: yes. Statistics by code: Figures that disagree between places in the document. Word: comments / tracked changes: no / no. Second round: With subscription. Confidentiality: Its Terms allow using the manuscript to improve the software; targeted advertising and third-party pixels in its policy. Institutional: Custom, no figure. source It has what Previum lacks: API, MCP server, chat about the manuscript, AI-generated text detector and a workspace with the PDF alongside.
PeerReviewAI. Price: $49 per manuscript; Journal Brief $2.99; English editing $19.99 extra (per manuscript). What is free: The first Journal Brief (summary, strengths, limitations and questions). Languages: English. Reviews the content: yes. References verified: PubMed and Crossref, with retraction notice. Statistics by code: CONSORT and STROBE checklists; no p recomputation. Word: comments / tracked changes: no / Journal formatting and English edits (add-on) as tracked changes. Second round: no. Confidentiality: States zero data retention with its AI provider. Institutional: no. source
Manusights. Price: €36 ($39) per professional review; 3 for €83; 5 for €129 (one-off). What is free: Readiness scan: a risk signal and one sample blocker. Languages: English. Reviews the content: yes. References verified: yes. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: Re-upload compared against the previous version. Confidentiality: Not checked. Institutional: no. source
Refine. Price: €49.99 per review (VAT incl.); 3 for €119.99; 10 for €299.99; subscriptions from $40 to $300/month (one-off or subscription). What is free: The first document, with an account. Languages: English. Reviews the content: Logic, mathematics and internal consistency. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: no. source
Thesify Reviewer. Price: €14.95 per review; 10 for €99.95; subscription €24.95/month with 3 a month (one-off or subscription). What is free: None for the reviewer (the 14-day trial is for the writing product). Languages: English. Reviews the content: Academic rubrics: thesis, evidence, clarity. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: no. source
Science AI Journal. Price: $20 for 50 credits; a professional review costs 30 (about $12); regional pricing (credits that do not expire). What is free: 25 credits on sign-up: not enough for a professional review (30). Languages: Not specified (interface in English). Reviews the content: yes. References verified: Only duplicate publication (title and abstract). Statistics by code: no. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: no. source
Review-it.ai. Price: $6.99 per document; $13.99 with fixes; $59/month unlimited (per document or subscription). What is free: None (its FAQ says so). Languages: Not declared. Reviews the content: yes. References verified: yes. Statistics by code: no. Word: comments / tracked changes: no / n/c. Second round: no. Confidentiality: Not checked. Institutional: no. source
ScholarsReview. Price: $4.99 per document without fixes; 4 for $14.99; with fixes from $11.99; $45/month unlimited (per document or subscription). What is free: Only the AI-text detector and “humanizer”. Languages: English. Reviews the content: yes. References verified: In packs of 4 or more. Statistics by code: no. Word: comments / tracked changes: no / n/c. Second round: no. Confidentiality: Not checked. Institutional: “Special pricing”, no figure. source
Octym (Proofig). Price: Not public: “per manuscript” for researchers and an annual license for institutions, all through sales (on request). What is free: None announced. Languages: English. Reviews the content: yes. References verified: OpenAlex, DOI and Retraction Watch. Statistics by code: Consistency of p values, percentages and CIs; image forensics. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: Annual license, no figure. source
PaperReview.ai (Stanford). Price: Free (academic demo). What is free: Everything: PDF up to 10 MB, first 15 pages only, result by email. Languages: English. Reviews the content: Yes, with arXiv literature (ML and CS venues). References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: no. source
q.e.d Science. Price: Free with an institutional email; no public price (academic account). What is free: The whole “Research Blueprint”, with an academic email. Languages: English. Reviews the content: From each claim to its evidence; life sciences. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: Free with an institutional email. source
SciSpace (agente de revisión). Price: Premium $12/month annual ($20 monthly); Advanced $70/month annual; the agent consumes plan credits (subscription). What is free: No free plan shown on its pricing page today. Languages: English. Reviews the content: Several reviewer “personas” and a novelty check. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: With subscription. Confidentiality: Not checked. Institutional: Enterprise on request. source
OpenReviewer. Price: Free: open model (8B) and demo (open source). What is free: Everything. Languages: English. Reviews the content: Machine-learning papers, in the style of their conferences. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: You host it. Institutional: no. source
Rigorous. Price: Not found: its websites did not resolve on 17 Sep 2026; the code is open (MIT) (open source). What is free: Presumably everything, unverified. Languages: English. Reviews the content: yes. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: no. source
AI language editors and pre-submission checks
Paperpal. Price: Prime €75/year on promotion (€22/month monthly); Pro €181.8/year (€51/month monthly) (subscription). What is free: 200 grammar edits a month; 5 daily uses of rewriting and AI Review; no reference check. Languages: Edits English; rewrites and translates in 50+ languages. Reviews the content: Section-by-section “AI Review”, experimental. References verified: Reference Check on Prime and Pro: retractions, broken DOIs, AI-generated citations. Statistics by code: no. Word: comments / tracked changes: Language highlights and comments / yes. Second round: With subscription. Confidentiality: ISO/IEC 42001 certified; policy not reviewed here. Institutional: Custom (contact). source
Paperpal Preflight. Price: $29 for the Word file with the language changes; the report is free (one-off, rechecks for 30 days). What is free: The full readiness report: 4 language assessments and 26 technical checks. Languages: English. Reviews the content: no. References verified: Reference format against the journal guide. Statistics by code: no. Word: comments / tracked changes: no / yes. Second round: Free rechecks for 30 days. Confidentiality: Not checked. Institutional: For publishers, no figure. source
Trinka. Price: Premium $48/year on promotion ($20/month monthly); reports by credits, separately (subscription + credits). What is free: 5,000 words a month in Lite mode and 4 credits; the free corrected Word file is read-only. Languages: Edits English, Spanish, Portuguese, Japanese, Chinese and Korean. Reviews the content: no. References verified: Quality report (age, retraction) by credits; does not check they exist. Statistics by code: no. Word: comments / tracked changes: no / Yes, on paid plans. Second round: With subscription. Confidentiality: No training and immediate deletion only on the Confidential Data plan ($300/year). Institutional: no. source
Writefull. Price: Premium €19/month or €135/year; Group €257/year for 2 seats (the minimum) (subscription). What is free: Permanent free plan with a daily quota they do not publish. Languages: English with its own models; other languages with a general model, limited on the free plan. Reviews the content: no. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / Publishers and institutions only (Writefull Revise). Second round: With subscription. Confidentiality: Not checked. Institutional: Group from €257/year (2 seats); Institution on request. source
Rubriq (AJE). Price: $16/month or $135/year ($11.25/month) (subscription). What is free: 7-day trial with a card; no free plan. Languages: Edits English; translates Chinese, Portuguese and Spanish into English. Reviews the content: no. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / yes. Second round: With subscription. Confidentiality: Documents deleted after 72 h; states it does not use generative AI. Institutional: Custom group pricing. source
Editage Digital Editing. Price: $29 per document (one-off). What is free: Preview of the edit before paying. Languages: English. Reviews the content: no. References verified: Count, age and self-citations; not existence. Statistics by code: no. Word: comments / tracked changes: no / yes. Second round: no. Confidentiality: Not checked. Institutional: no. source
Scribbr AI Proofreader. Price: Not published: shown after uploading the document (third parties cite $9.95 for 30 days) (one-off). What is free: Writing score and error count, without seeing the corrections. Languages: US English; .docx only. Reviews the content: no. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / yes. Second round: Unlimited uploads for 30 days. Confidentiality: Document deleted after correction. Institutional: no. source
Grammarly Pro. Price: €12/month on its euro page ($30/month monthly or $144/year in dollars) (subscription). What is free: Spelling, grammar and tone; 100 AI prompts a month. Languages: Full English; suggestions in 20+ languages. Reviews the content: no. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: With subscription. Confidentiality: Not checked. Institutional: Enterprise on request. source
QuillBot Premium. Price: €8.33/month annual (€99.95/year); €19.95/month monthly (subscription). What is free: Paraphrase up to 125 words; basic grammar. Languages: Grammar in 6 languages (Spanish included); paraphrasing in 23. Reviews the content: no. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: With subscription. Confidentiality: Not checked. Institutional: Team on request. source
DeepL Write Pro. Price: A €6.99/month add-on (annual) on top of a €7.49/month DeepL Pro plan: €14.48/month minimum, VAT included (subscription). What is free: Free Write: up to 1,500 characters per pass, no styles. Languages: English, Spanish, Portuguese, French, German, Italian, Chinese, Japanese and Korean. Reviews the content: no. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: With subscription. Confidentiality: Free: texts may be used for training; Pro: no. Institutional: Team €24.99/user/month. source
Wordvice AI. Price: Premium $9.95/month annual on promotion ($19.95 monthly); Premium PRO $26.95/month annual (subscription). What is free: 500 words per submission and 5,000 a month, 2 modes. Languages: Grammar in 11 languages (Spanish, Portuguese and French included). Reviews the content: no. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: With subscription. Confidentiality: Not checked. Institutional: Team $9.95/user/month. source
Jenni.ai. Price: Free; Plus $12/month; Pro $29/month (subscription). What is free: 3 “Reviews” scans (10 a month); 5 chat messages. Languages: Multilingual interface; review designed for English. Reviews the content: “Claim Confidence”: classifies each claim. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: With subscription. Confidentiality: Not checked. Institutional: no. source
Yomu.ai. Price: Pro $10/month ($120/year); Ultra $17/month (subscription). What is free: No defined free plan; standalone free tools. Languages: English. Reviews the content: “Get Feedback” inside the editor. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: With subscription. Confidentiality: Not checked. Institutional: no. source
General-purpose chats
ChatGPT Plus. Price: Plus €23/month (VAT incl.); Go €8/month; free with limits (subscription). What is free: Unlimited text chats; limited files and context. Languages: All. Reviews the content: Whatever you know how to ask for. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: If you ask again. Confidentiality: By default it may use what you write for training (opt-out available). Institutional: Edu on request. source
Claude Pro (con el complemento de Word). Price: $17/month paid annually ($20 monthly), before tax (subscription). What is free: Chat with per-session usage limits; the Word add-in requires a paid plan. Languages: All. Reviews the content: Whatever you know how to ask for. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / Yes: the add-in edits in native tracked changes. Second round: If you ask again. Confidentiality: Not checked. Institutional: Team $20-25/user/month. source
Human editing and review
Editage (edición humana). Price: From $0.06/word (Advanced: $210 for 3,500 words); Premium from $0.13/word; Scientific Editing Pro $0.24/word (per word, 1 to 16 days). What is free: None; instant quote. Languages: English. Reviews the content: Only in Scientific Editing Pro: report by a journal reviewer. References verified: no. Statistics by code: no. Word: comments / tracked changes: n/c / yes. Second round: Free re-editing for 365 days (Premium). Confidentiality: Not checked. Institutional: no. source
Enago (edición humana). Price: Copy Editing $174 for 3,000 words ($0.058/word, 6 days); Substantive $252; Top Impact $600 to $900 ($0.20/word) (per word, 1 to 6 days). What is free: None. Languages: English. Reviews the content: Only in Top Impact: mock peer-review report by people. References verified: no. Statistics by code: no. Word: comments / tracked changes: n/c / yes. Second round: “Rejection Shield” for 365 days on Substantive and Top Impact. Confidentiality: Not checked. Institutional: no. source
Enago AI Peer Review Lite (IA + validación humana). Price: $99 on offer ($149 list), 4 days; professional review with 1 to 3 reviewers $272 to $799, 5 business days (per manuscript). What is free: None for the review service. Languages: English and Japanese. Reviews the content: yes. References verified: no. Statistics by code: no. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: no. source
AJE (edición humana). Price: Standard $299 for 6,000 words ($239 with the 20% on screen); Premium $560; VIP $759; Scientific Editing $3,230; Pre-Submission Peer Review from $500 (per manuscript, 4 to 14 days). What is free: Free English assessment (a score, not a correction). Languages: English. Reviews the content: Structure and argument comments from VIP ($759); pre-submission peer review from $500. References verified: no. Statistics by code: no. Word: comments / tracked changes: One round of in-line comments (VIP) / yes. Second round: Unlimited re-edits for 3 years (Premium). Confidentiality: Not checked. Institutional: Group accounts and volume discounts. source
Wiley Editing Services. Price: Quick Language Fix $425 (5,001 to 6,000 words, 7 days); In-depth $696; Premium $877 to $1,081; Rapid Statistical Review $830 (per word band, 3 to 7 days). What is free: One-minute English score (a funnel to the purchase). Languages: English. Reviews the content: Premium Editing and Top Journal Editing ($1,500). References verified: no. Statistics by code: Human reanalysis: Rapid Statistical Review, $830, 5 days. Word: comments / tracked changes: n/c / yes. Second round: n/c. Confidentiality: Not checked. Institutional: no. source
Springer Nature Author Services. Price: Silver from $91; Gold from $312; Scientific Editing from $1,545; the exact price only after uploading the manuscript (per manuscript). What is free: None. Languages: English; translates Spanish and Portuguese into English. Reviews the content: Scientific Editing (from $1,545). References verified: no. Statistics by code: no. Word: comments / tracked changes: n/c / yes. Second round: Unlimited re-editing for 1 year (Gold). Confidentiality: Not checked. Institutional: no. source
Elsevier Language Editing. Price: Standard $320 (3,501 to 6,000 words, 7 days); Express $524; Plus $690; from $95 up to 500 words (per word band). What is free: None. Languages: English. Reviews the content: Plus: logic, structure and an assessment report. References verified: Plus: consistency and format, not existence. Statistics by code: no. Word: comments / tracked changes: n/c / yes. Second round: 12 months of re-editing (Plus); refund if rejected for the English. Confidentiality: Not checked. Institutional: Group Deals. source
Scribbr (edición humana). Price: 5,000 words: €95 in 7 days, €133 in 3 days, €245 in 24 h, plus a €20 setup fee (per word and deadline). What is free: None (a 2,000-word sample if the document exceeds 20,000). Languages: English (US, UK, AU); separate sites for other languages. Reviews the content: Structure Check and Clarity Check, €30 more each. References verified: Citation Editing at €2.20 per source: format, not existence. Statistics by code: no. Word: comments / tracked changes: yes / yes. Second round: no. Confidentiality: Not checked. Institutional: no. source
Tools sold to journals
Penelope.ai. Price: £750/year for journals with fewer than 500 submissions; up to £4,850 with 5,000 (annual license per journal). What is free: For the author, if their journal has it integrated. Languages: English. Reviews the content: no. References verified: Citation and list matched, and their order; not existence. Statistics by code: Abstract structure (PRISMA, CONSORT) and declarations. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: Yes, for journals, with a public price. source
SciScore. Price: $39.99 for 3 credits for academics (about $13 per report); $49.99 for companies (credits). What is free: None announced. Languages: English. Reviews the content: no. References verified: no. Statistics by code: Biomedical reporting checklists (CONSORT, ARRIVE, MDAR, NIH) and RRIDs. Word: comments / tracked changes: no / no. Second round: no. Confidentiality: Not checked. Institutional: Custom campus credits. source
What Previum does not do today
It does not return your Word file with tracked changes: it returns your Word file with every objection as a comment in the margin, attached to the sentence it criticizes. If you want someone to rewrite your sentences, look at Paperpal Preflight, Editage Digital Editing, Scribbr or Claude’s Word add-in.
It does not read figures: it reads the text and the tables. Reviewer3 and Octym do look at images.
It has no API, no MCP server and no chat about the manuscript. Reviewer3 has all three.
It does not detect AI-generated text or count self-citations; Reviewer3, Paperpal and Trinka do.
Nobody reads your manuscript: it is two simulated reviewers and a simulated editor, plus checks run with code. If you need a human signature, human editing is in the table, with its price.
The public benchmark
Only one tool in the table publishes an open benchmark another tool can be measured against: Reviewer3 publishes ReviewBench, with 1,000 eLife articles and the comments from the human reviewers, from Reviewer3 and from two general-purpose models, with an automatic judge and its code. We ran our engine on 200 of those articles with their code and their judge, and put the averages side by side.
On agreement with human reviewers there is no significant difference (93.4% versus 95.6% of the claims the humans address; 67.9% versus 70.4% with the same stance). They win on pointing at a specific claim (77.1% versus 73.1%); we win on anchoring in the text (98.1% versus 83.0%), on the objection being able to undermine the claim (97.2% versus 89.7%) and on saying why it matters (100% versus 97.4%). The JSON with intervals is on /en/evidence.
References tell a similar story: they publish 98.5% on 476 citations they do not itemize; we publish 88.2% on the 636 of the original Walters and Wilder benchmark, one by one (92.3% of the fabricated ones caught, 86.4% of the real ones recognized). For the rest of the table I have found no comparable benchmark; if there is one, write to me and I will add it.
Metric (their benchmark, 200 articles)
Reviewer3
Previum
Addresses the claims human reviewers address
95.6%
93.4%
With the same stance as the humans
70.4%
67.9%
Points at a specific claim of the paper
77.1%
73.1%
Carries an anchor in the text (table, figure, quote)
83.0%
98.1%
Could undermine the claim
89.7%
97.2%
Says why it matters
97.4%
100%
Figures measured on 6 September 2026 over 200 eLife articles from ReviewBench, with their code and their judge. The first two rows do not differ in a statistically significant way; the next four do.
These work on all forty rows, mine included, and on human editing too. If a tool makes any of them hard to answer, that difficulty is itself the answer.
1. Who set the standard, and is that person named?
Every review tool encodes somebody’s opinion of what matters in a manuscript, and the useful question is whose. Look for a named person with a traceable record in your field: someone who reviews for these journals, publishes in them, or edits for them. “Built with leading researchers” is not a name. Check the about page, then that name in Google Scholar or ORCID.
2. Does it quote your text, or talk about it in the abstract?
The fastest test of whether a review is real. A criticism that quotes the sentence it objects to can be checked, argued with and acted on; “the methodology could be strengthened” can be written without reading anything. Take the first output you get and count the criticisms containing a verbatim sentence of yours. Zero means you are holding a description of papers in general.
3. Does it verify the references, or repeat them?
A language model can produce a perfectly formed citation that refers to nothing, and telling it not to invent changes little, since it cannot check itself. Ask whether references are checked against an index and which one, then verify by hand: take three citations it produced and search them in Crossref or PubMed. One miss and you stop using it for citations.
4. Does it tell you what to fix, or only that something is wrong?
Diagnosis without treatment is where most automated review stops. “Your sample size is not justified” is true and you already suspected it; what you need is which justification your design calls for, what to compute, and what sentence goes into the manuscript. Read one full criticism and ask whether you could act on it tomorrow morning without consulting anybody.
5. What happens to your manuscript afterwards?
You are uploading unpublished work, sometimes with clinical material behind it. What matters is whether the file is stored, for how long, whether it trains anything, and whether you can have it deleted. This applies to every category, mine included. Read the privacy policy rather than the marketing page and search it for “train”, “retain” and “delete”; if those words never appear, the silence is information.
6. Does it rewrite your paper, and what does that do to your authorship?
There is a real line between a tool that tells you a paragraph does not work and one that hands you a replacement paragraph. Cross it often and you are submitting sentences you did not write and cannot defend when a reviewer asks about them. Read your journal’s instructions for authors, usually under a heading on generative AI or research integrity: responsibility for the text sits with people who can answer for it.
7. Is the criticism specific to your field, or true of any paper?
Psychology and health sciences have objections that barely exist elsewhere and that sink manuscripts here: what counts as adequate reliability evidence, measurement invariance before comparing latent scores, causal language on a cross-sectional design, effect sizes with intervals instead of a naked p value. Run a manuscript you know well and ask whether anything came back that a reader outside your field could not have said.
8. Can you tell whether it read the whole thing?
Long manuscripts can get truncated, and a review of your introduction presented as a review of your paper buys false confidence about the part that gets you rejected: the fatal objections live in method and analysis, in the middle of the file. Plant the test yourself: put a checkable oddity deep in the results, a reported degrees of freedom that cannot match your sample size, and see whether it comes back.
The twenty-minute test
Every claim on this page, mine included, is checkable in one sitting with a manuscript whose flaws you already know: the best candidate is a paper of yours rejected after review, because you hold the reports and therefore the answer key.
Run the same file twice. The overlap between the two outputs is roughly the part you can rely on.
Search three references it produced in Crossref or PubMed. Any miss disqualifies it for citation work.
Count the criticisms that quote a sentence of yours, and those that name a concrete next step.
Plant one checkable error deep in the results before uploading, and see whether it comes back.
When something else suits you better
Plainly, because a comparison the author always wins is useless for deciding:
If you put many manuscripts through every month, a subscription: Reviewer3 charges $19 a month for unlimited reviews, and once you go past two or three a month that beats €12 per report.
If you need guaranteed native English, with a certificate for the journal: human editing (Editage, Enago, AJE, Scribbr, or the services from Wiley, Elsevier and Springer Nature). It costs from $95 to over $1,000 and takes days, but a native speaker signs it.
If you are going to NeurIPS, ICLR or ICML: PaperReview.ai, from Stanford, is free, built for that world and pulls the literature from arXiv.
If your manuscript is mathematical (theoretical economics, statistics, theoretical computer science): Refine checks the formal reasoning; mine does not.
If you are an editor screening at volume: Octym looks at images and paper mills; Penelope and SciScore sit inside the journal’s submission flow.
If what you want is to polish the English paragraph by paragraph while you write: DeepL Write, Grammarly, Paperpal, Trinka or Writefull live in the editor. Previum arrives once the manuscript exists.
If you need tracked changes in the Word file: today Paperpal Preflight and Editage Digital Editing give them for $29, as do Scribbr AI Proofreader and Claude’s Word add-in. Previum returns comments in the margin, not changes.
Frequently asked questions
Which is the cheapest tool to review a manuscript?
Entirely free: PaperReview.ai (English only, 15 pages, machine-learning venues) and q.e.d Science (with an institutional email). With a full one-off report: ScholarsReview $4.99, Previum €12, Review-it.ai $6.99 and Reviewer3 $11. What separates them is less the price than what they check: of those four, only Previum recomputes p values with code and returns your Word file with comments in the margin; only Reviewer3 has an API, a chat and an AI-text detector.
Does any of them review manuscripts in Spanish?
Reviewing the content and returning the report in Spanish is what Previum does (also in English, Portuguese and French, with the manuscript in any of them). Editing the Spanish prose is what Trinka, QuillBot, DeepL Write, Wordvice AI and, less deeply, Grammarly do. General-purpose chats work in any language, with whatever quality you know how to ask for. The rest of the table works in English and declares no other language.
What is the difference between “verifying references” and “checking reference format”?
Verifying means asking a bibliographic database whether the cited work exists with that title, those authors and that DOI: Previum does it (against eight databases, already in Basic), as do Reviewer3, PeerReviewAI, Manusights, Paperpal on its paid plans, Octym and, in packs, ScholarsReview. Checking format means making sure the citation is well written and matched to the list, without asking whether it exists: that is what Penelope, Preflight, Editage Digital Editing, Scribbr’s Citation Editing and human editing do. The cell in the table tells them apart.
Where do the figures come from and when do they expire?
Every price was read on the tool’s own page on 17 September 2026 and checked by a second reader the same day; where they disagreed, the second reader’s figure is the one here. Several figures are promotional (Paperpal, Trinka, Wordvice AI, Enago Lite) and the cell says so. Every row carries its source: look at it before deciding, and if you spot an outdated one, write to me and I will correct it with the date.
Why trust a comparison written by a competitor?
Not blindly: that is why every row links to its source, the table includes what Previum does not do, there is a section on the cases where another tool suits you better, and the benchmark figures come from Reviewer3’s own benchmark, with their code and their judge. If you find an error, write to me and I will fix it with the date of the change.
Before you decide with a table, decide with your manuscript: upload it and read the finding that decides, with the quoted sentence and the fix, plus your references checked against eight databases and your p values recomputed. Basic report free with your account.