Chicago Citation Checker
Paste your Chicago notes-bibliography bibliography and get each likely formatting slip flagged: a first author who is not inverted, a later author who is, an ampersand where Chicago wants “and”, a title in sentence case, an outdated DOI link, a missing final period, an unneeded access date, entries out of A–Z order, and repeated sources. Free, no sign-up, and nothing leaves your browser.
What this checker looks for
- The first author inverted to Last name, First name — while later authors stay in natural First Last order.
- The word “and” (not &) before the final author.
- Titles in headline-style Title Case rather than sentence case.
- DOIs as a clean https://doi.org/10.xxxx link.
- A terminal period (unless the entry ends in a DOI or URL).
- An access date on an entry that already has a publication year — Chicago reserves access dates for undated online sources.
- Alphabetical order of the list and duplicate entries.
Every finding is advisory and links to the relevant Chicago guideline. The checker is deterministic — it never uploads your text, never uses AI, and never auto-rewrites your references. It targets notes-bibliography bibliography entries only (footnotes, author-date reference lists, and other styles are not checked yet).
How to Use the Chicago Citation Checker
- Paste your bibliography. Put one entry per line, or separate wrapped entries with a blank line. Paste the bibliography only — footnotes and endnotes are written differently and are not checked.
- Read the list-level findings first. Entries out of A–Z order and repeated sources affect the whole list, so they appear above the individual entries.
- Work through each flagged entry. A finding says what looks wrong, offers a corrected fragment to copy when it can, and links to Chicago guidance. High confidence means the pattern is almost always an error; Worth a look means it often is.
- Paste the list again after editing. Entries that now pass drop out of the results.
The Chicago Rules the Checker Applies
The checks follow the notes-bibliography system in The Chicago Manual of Style (18th ed., 2024), the form most used in history and the humanities. The bibliography differs from the notes in the same paper: its entries invert the first author and separate elements with periods, where notes keep natural name order and use commas.
| Element | Chicago bibliography form | Flagged when |
|---|---|---|
| First author | Smith, John — surname first | the entry opens with a given name, as in John Smith |
| Later authors | Smith, John, and Jane Doe — natural order | a later author is inverted, as in and Doe, Jane |
| Connector | the word and | an ampersand (&) joins the last two authors |
| Title | headline-style Title Case | every principal word after the first is lowercase |
| DOI | https://doi.org/10.xxxx/yyyy | the link uses dx.doi.org or http:// |
| Ending | a period | the entry ends with no punctuation and no link |
| Access date | only when the source has no publication or revision date | an entry has both a year and “accessed …” |
| List order | A–Z by the first author’s surname | an entry sorts before the one above it |
Rules from The Chicago Manual of Style, 18th ed., notes-bibliography system.
One rule the checker does not test: Chicago 18 lists up to six authors in a bibliography entry, and for seven or more gives the first three followed by et al. In notes, a source with four or more authors is cited by the first author and et al.
Worked Example
Choose Try a sample to load three invented entries. The checker reports 6 likely issues to review across 3 entries, and one entry passes:
- The list: the entries run Smith, Brown, Adams, so entries 2 and 3 are each flagged as out of A–Z order. It is one problem — the list is reversed.
- Entry 1 begins John Smith (the fix is Smith, John) and its article title, “The effects of sleep on memory,” is in sentence case; headline style gives “The Effects of Sleep on Memory.”
- Entry 3 uses & where Chicago wants Adams, Rachel, and Anna Doe, and ends without a period.
- Entry 2 — Brown, Karen L. The Grammar of Rivers. New York: Academic Press, 2021. — passes untouched.
What a Plain-Text Check Cannot See
- Author-date lists. Chicago’s author-date system puts the year right after the author and follows different rules. A clean result here does not validate an author-date reference list.
- Formatting. Italics for book and journal titles and the hanging indent do not survive pasting. Add the indent with the Hanging Indent Formatter.
- Whether the details are true. A wrong volume, a mistyped DOI or a source that does not exist all pass.
- Group authors and the rest. Authors such as “United Nations” are recognized by their institutional words and left alone. The checker does not test the author count, the order of publication details, or your footnotes.
Which Citation Checker Do You Need?
Each checker tests one style, so use the one your assignment names. If you are not sure which style a list uses, run it through the Citation Style Identifier first. To write the matching footnotes, use the Chicago Footnote Generator.
| Your style | Use | Reference list is called |
|---|---|---|
| APA 7 | APA Citation Checker | References |
| MLA 9 | MLA Citation Checker | Works Cited |
| Chicago 18 | This page | Bibliography |
| Harvard | Harvard Citation Checker | Reference list |
| IEEE, Vancouver, AMA | IEEE, Vancouver or AMA checker | Numbered references |
Frequently Asked Questions
- What does a Chicago citation checker check?
- This one reads each bibliography entry for a first author who is not inverted, later authors who are, an ampersand instead of “and”, a title in sentence case, an outdated DOI link, a missing final period, and an access date on a dated source. It also checks the list for entries out of A–Z order and for repeated sources.
- Does this work for Chicago author-date style?
- No. It targets the notes-bibliography system. Author-date reference lists put the year after the author and differ in punctuation and capitalization, so findings on such a list would be unreliable and a clean result would mean little.
- How are authors written in a Chicago bibliography?
- The first author is inverted and later authors stay in natural order: Smith, John, and Jane Doe. Chicago 18 lists up to six authors; with seven or more, give the first three followed by et al. The word “and”, not an ampersand, joins the last two.
- Should Chicago titles be in Title Case?
- Yes. Chicago uses headline-style capitalization for titles of books, articles and journals: capitalize the first and last words and every principal word, and lowercase articles, prepositions and conjunctions. The checker flags a title only when all its longer principal words start lowercase.
- When does Chicago need an access date?
- Only when an online source has no publication or revision date. If the entry already carries a year, the access date is usually unnecessary, so the checker marks it Worth a look. Keep it if your instructor or publisher asks for access dates.
- What is the difference between a Chicago bibliography and the notes?
- The notes cite a source at the point of use, with the author in natural order and elements separated by commas. The bibliography lists all sources alphabetically at the end, with the first author inverted and elements separated by periods. This checker reads the bibliography.
- Is my bibliography uploaded anywhere?
- No. The checker runs entirely in your browser; nothing you paste is sent to a server or stored.