Academic style checker for APA, MLA, Chicago and AP

Paste a paragraph or a whole paper, pick the style guide your instructor or editor asked for, and see every citation, number and punctuation slip marked up the way a copy editor would, with the rule and the fix beside it.

APA Style · 7th edition (2020)

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Recent studies suggests that sleep quality affects memory consolidation in undergraduate students. Walker and Stickgold, 2004 found that subjects¹ who slept after learning recalled twelve² percent more word pairs than those who stayed awake (Walker and Stickgold, 2004³). The data shows⁴ a similar pattern in adolescents, e.g.⁵ those aged 13-17⁶ (Carskadon et al⁷ 2011). ⁸Each participant completed 3⁹ questionnaires, a sleep diary and an actigraphy watch. As Diekelmann & Born (2010)¹⁰ note, "sleep is a state that optimizes the consolidation of newly acquired information" (Diekelmann & Born, 2010)¹¹. When a student reports poor sleep, he or she¹² may also report lower grades, and you¹³ can't¹⁴ separate the two easily. References Walker, M. P., & Stickgold, R. (2004). Sleep-dependent learning and memory consolidation. Neuron, 44(1), 121–133. Diekelmann, S., & Born, J. (2010). The memory function of sleep. Nature Reviews Neuroscience, 11(2), 114–126. Stickgold, R. (2005). Sleep-dependent memory consolidation. Nature, 437(7063), 1272–1278.

131 words · 15 sentences · 32 APA rules checked

4errors

4warnings

6notes

1
“subjects” for people
“subjects” → “participants”
APA 7 prefers “participants” (or a specific term such as “students”) for people in research.
2
Spelled-out number 10 or above
“twelve” → “12”
APA uses numerals for 10 and above (unless the number starts a sentence).
3
“and” inside a parenthetical citation
“(Walker and Stickgold, 2004” → “(Walker & Stickgold, 2004”
APA uses an ampersand (&) between author names inside parentheses.
4
“data” as singular
“data shows” → “data show”
APA treats “data” as plural: the data are, the data show.
5
Comma after e.g. / i.e.
“e.g.” → “e.g.,”
APA and Chicago follow “e.g.” and “i.e.” with a comma.
6
Hyphen in a number range
“13-17” → “13–17”
Number and page ranges take an en dash (–), not a hyphen.
7
Malformed “et al.”
“et al” → “et al.”
“et” is a whole Latin word (no period); “al.” is an abbreviation (period required).
8
Two spaces after punctuation
“. ” → “. ”
All four guides now use one space after a full stop or other punctuation.
9
Numeral below 10
“3” → “three”
APA spells out zero to nine, except with units of measurement, statistics, ages, times, dates, scores and percentages.
10
Ampersand in a narrative citation
“Diekelmann & Born (2010)” → “Diekelmann and Born (2010)”
In running text APA spells out “and”: Smith and Jones (2020).
11
Direct quotation without a page number
“"sleep is a state that optimizes the consolidation of newly acquired information" (Diekelmann & Born, 2010)” → “"sleep is a state that optimizes the consolidation of newly acquired information" (Diekelmann & Born, 2010, p. X)”
APA requires a page (or paragraph) locator for every direct quotation.
12
Binary pronoun pair
“he or she” → “they”
APA 7 endorses singular “they”; MLA and Chicago accept it too.
13
Second person
“you”
Research papers rarely address the reader as “you”; rephrase in third person.
14
Contraction
“can't”
Academic styles expect contractions to be written out (do not, it is).

Citations vs. reference list

2 in-text citations matched an entry.

In the list but never cited

Stickgold, R. (2005). Sleep-dependent memory consolidation. Nature, 437(7063), 1272–1278.…

Check each entry’s format with the citation checker.

AI style review

A second read by an AI editor briefed on APA Style: judgment calls the rules can’t make, such as clarity, bias-free wording and citation placement.

Everything else a style check needs

Citation checkerValidate reference-list entries against APA, MLA or Chicago.Tone & formalityScore how formal your prose sounds and see what drags it down.ReadabilityFlesch ease, grade levels and vocabulary sophistication.Passive voiceHighlight every passive construction and who is missing.Sentence varietySee the rhythm of your sentence lengths and repeated openers.Title caseCapitalise titles the APA, MLA, Chicago or AP way.Academic phrasebankPhrases for introductions, evidence, contrast and conclusions.

One sentence, four rulebooks

Style guides disagree for good reasons. APA serves the sciences, where readers need to know when a finding was published, so the year sits in every citation. MLA serves literary study, where readers need to find the passage, so the page number does the work and the year disappears. Chicago’s notes keep the prose clean for historians who cite archives, and AP writes attribution into the sentence because newspapers have no reference list.

Switch between the tabs to watch the same finding from Walker and Stickgold’s 2004 sleep study change its citation, its numbers and its source entry. Once you can see why each guide makes its choices, the rules stop feeling arbitrary. On ahaboo, you build understanding by doing: zooming into a leaf to follow photosynthesis, or reasoning through marginal versus effective tax rates.

Participants who slept after training recalled 20% more pairs than the wake group (Walker & Stickgold, 2004, p. 122).

Citation: Author–date, comma before the year, “p.” before the page, & between two authors.
Numbers: Numerals for 10 and above; % symbol after numerals.
Reference: Walker, M. P., & Stickgold, R. (2004). Sleep-dependent learning and memory consolidation. Neuron, 44(1), 121–133. https://doi.org/10.1016/j.neuron.2004.08.031

How the checker works

The first pass is a rule engine that runs in your browser. Each rule is a precise pattern taken from the manual (a missing comma before the year in an APA citation, a spelled-out “twelve” where APA wants a numeral, a “Sept. 12th” where AP wants “Sept. 12”) paired with the reason and, where the fix is unambiguous, the corrected text. Because it is deterministic, the same draft always gets the same result, and it works offline once the page has loaded.

Patterns cannot judge everything. Whether a claim needs a citation, whether a phrase is biased, or whether a sentence is clear are editorial calls, so the optional AI style review sends your text to a language model briefed on the guide you chose and returns its top issues as quote → fix pairs. It never runs unless you press the button.

Which style guide should you use?

Guide	Typical fields	In-text citation	Source list
APA 7	Psychology, education, nursing, business, social sciences	(Nguyen, 2021, p. 4)	References
MLA 9	English, languages, cultural studies	(Nguyen 4)	Works Cited
Chicago 17	History, art history, theology, book publishing	Footnote¹ or (Nguyen 2021, 4)	Bibliography / References
AP	Journalism, public relations, corporate communications	“…, Nguyen said.”	None

Guides with worked examples

APA in-text citationsParenthetical and narrative formats, with a live builder.
MLA in-text citationsAuthor–page citations for every source situation.
APA headingsAll five levels, previewed on a real outline.
APA vs MLAThe same source cited both ways, difference by difference.
Chicago footnotesFull notes, short notes and the bibliography entry.
MLA 9th editionThe nine core elements, stepped through one at a time.

Questions

Is this academic style checker free?

Yes. The rule checks, citation validator, tone, readability, passive voice, sentence variety and title case tools are free and run in your browser with no sign-up. The optional AI review is also free, with a fair-use limit per visitor.

Which style guide editions does it follow?

APA Publication Manual 7th edition (2020), MLA Handbook 9th edition (2021), The Chicago Manual of Style 17th edition (2017) and the current AP Stylebook. The 18th edition of Chicago (2024) changed few of the rules checked here.

Does it check page layout, margins and fonts?

No. It checks the words on the page: citations, numbers, punctuation, capitalisation, bias-free language and tone. Margins, running heads and line spacing live in your word processor’s settings, and the guides on this site list the values.

Is my writing stored or used for training?

Rule checks happen entirely in your browser. Your latest draft is saved only in your own browser’s local storage so it survives a reload; clear it any time. Text is sent to the AI editor only when you press an AI button, and it is not stored by this site.

Can it replace my instructor’s rubric or a journal’s author guidelines?

No. Instructors and publishers often modify a style guide. Use the checker to catch mechanical errors quickly, then confirm anything unusual against the assignment sheet or the journal’s instructions.