Citation & Reference Tools
The tools you reach for once the references exist: check a list against APA, MLA, Chicago, Harvard, IEEE, Vancouver or AMA, convert between BibTeX, RIS, EndNote and Word, find and fix DOIs, and catch duplicates and retracted papers before a reviewer does. Free, no sign-up.
Citation & Reference Tools
41 tools · free, no sign-up
Bibliography Alphabetizer
Alphabetize your bibliography, works cited, or reference list instantly. Supports APA, MLA, and Chicago sorting rules.
DOI Validator & Resolver
Validate and resolve DOIs (Digital Object Identifiers). Check if a DOI is valid and get the full metadata for any academic article.
Et Al. Rules Calculator
Determine when to use et al. in your citations. Get the correct rules for APA 7th, MLA 9th, Chicago, Harvard, and Vancouver.
Citation Checker (APA 7)
Paste your APA 7 reference list to catch likely formatting issues — author order, year, DOI format, sentence case, alphabetical order, and duplicates. Free and unlimited.
Citation Checker (MLA 9)
Paste your MLA 9 Works Cited list to catch likely formatting issues — author inversion, the 'and' connector, Title Case, DOI format, alphabetical order, and duplicates. Free and unlimited.
Reference Extractor
Upload a Word (.docx) or text file — or paste your paper — to extract the reference list, find every in-text citation, collect DOIs, and spot citations missing from the list. Runs entirely in your browser.
Citation Style Converter
Convert a reference list from one citation style to another: match each reference to its Crossref record, confirm it, and get the list in APA, MLA, Chicago and more.
Citation Counter
Count the number of citations and references in your academic paper. Detect parenthetical, narrative, and numbered citation formats across APA, MLA, Chicago, and more.
Citation Checker (Chicago)
Paste your Chicago-style bibliography to catch likely formatting issues — author inversion, punctuation, Title Case, DOI/URL format, alphabetical order, and duplicates. Free and unlimited.
BibTeX Key Generator
Generate clean, consistent BibTeX citation keys from author, year, and title — in common formats like authorYEARfirstword. Paste a reference or enter fields and copy the key.
DOI to BibTeX Converter
Paste a DOI and get a complete BibTeX entry — author, title, journal, volume, year, and pages filled in automatically from Crossref. Copy it straight into your .bib file.
Citation Checker (Harvard)
Paste your Harvard reference list to catch likely formatting issues — author initials, year placement, italics markers, alphabetical order, and duplicates. Free and unlimited.
Author Name Formatter
Convert author names to correct citation formats — APA (Last, F. M.), MLA (Last, First), and Chicago — one name or a whole list at once, with multi-author joining rules applied.
Duplicate Citation Finder
Find duplicate and near-duplicate entries in your reference list — catches the same source cited twice with small formatting differences before your grader does.
PubMed to BibTeX Converter
Turn PMIDs and PMCIDs into BibTeX @article entries — NLM journal abbreviations, full page ranges, DOI, and the PMID as a field, a note or a biblatex eprint.
URL to BibTeX Converter
Paste web addresses and get BibTeX @misc entries with the link in howpublished and an access-date note, or biblatex @online entries with url and urldate.
ISBN Converter
Convert ISBN-10 to ISBN-13 and back, validate both check digits (mod 11 with X, and mod 10 with weights 1 and 3), and see the arithmetic — for one ISBN or a list.
ISBN Barcode Generator
Draw the EAN-13 barcode for an ISBN, with an optional EAN-5 price add-on, the digits below and ISBN 978-… above, and download it as print-ready SVG or PNG.
ISSN Validator
Check the format and mod-11 check digit of one ISSN or a whole list, with the working shown — plus print, online and linking ISSNs (ISSN-L) explained.
Call Number Sorter
Put Library of Congress or Dewey Decimal call numbers into correct shelf order, with each call number's class, Cutter numbers, date and volume labelled.
Journal Abbreviation Finder
Search about 38,000 journals by title, abbreviation or ISSN and get the NLM/MEDLINE and ISO abbreviations, an ISO 4 full-stop form, and print and online ISSNs.
Retraction Checker
Paste DOIs or a whole reference list and check each DOI in Crossref for retractions, expressions of concern, corrections and withdrawals — Retraction Watch data included.
DOI Link Formatter
Find every DOI in a reference list however it is written and rewrite them all as https://doi.org/ links (APA 7), doi:10… (AMA), doi: 10… (IEEE) or bare DOIs.
RIS File Validator
Check a .ris export record by record — tag lines, TY and ER, unknown tags, missing fields, duplicates and encoding — fix what is safe to fix, and download a clean file.
Citation Style Identifier
Paste references and see which style they follow — APA, MLA, Chicago, Harvard, IEEE, Vancouver or AMA — with a confidence and the evidence behind each verdict.
BibTeX Cleaner & Validator
Validate and tidy a .bib file: required fields, duplicate keys and DOIs, undefined macros, page dashes, month macros, protected capitals and sorting — with every change listed.
BibTeX to Word Source Manager Converter
Turn BibTeX or RIS into a Sources.xml file for Word's Source Manager, so Word inserts the citations and builds the bibliography itself, in any of its styles.
DOI Finder
Paste a reference list and find each work's DOI on Crossref, with the matched record set beside your reference to accept or reject, then copy the list with DOIs added.
Open Access Finder
Check DOIs against OpenAlex for open-access status — diamond, gold, hybrid, bronze, green or closed — with the best free copy, its version and its licence.
ORCID Publication List Generator
Turn an ORCID record into a formatted publication list for a CV or grant application — APA, MLA, Chicago, Harvard, Vancouver or IEEE — with .bib and .ris exports.
Citation Checker (IEEE)
Paste an IEEE reference list to catch likely issues — [n] numbering, initials before surnames, et al. after six authors, quoted titles, vol./no./pp., months and the doi: form.
Citation Checker (Vancouver)
Paste a Vancouver (NLM/ICMJE) reference list to catch likely issues — numbering by first citation, Surname AB names, six authors then et al., journal abbreviations and locators.
Citation Checker (AMA)
Paste an AMA 11 reference list to catch likely issues — Surname AB names, three authors then et al., sentence-case titles, Year;Vol(Issue):pages, full page ranges and doi:10.
Numbered Citation Order Checker
Check that numbered citations — [1], (2) or superscripts — follow the order of first citation, find gaps and uncited or missing references, and get the text and list renumbered.
Reference Age Checker
Paste a reference list in any style to read each source's publication year, flag sources older than your cutoff (five years by default), and see the median age and a chart by year.
Creative Commons Attribution Generator
Build a Creative Commons credit in TASL form (title, author, source, licence) for CC BY, CC0 and other licences, as linked text, HTML and plain text for print.
Citation Chaser
Enter seed DOIs and find the works they cite (backward) and the works that cite them (forward) through OpenAlex, then export each list as RIS for screening.
Journal Metrics Lookup
Look up a journal by title or ISSN on OpenAlex: works, citations, h-index, 2-year mean citedness, open-access share, DOAJ and MEDLINE status, and APC. Not the JIF.
MeSH Term Finder
Search NLM's MeSH vocabulary for headings, entry terms, tree numbers and narrower terms, then build a PubMed search string with explode, major-topic and title/abstract options.
EndNote XML Converter
Convert an EndNote XML export to RIS, BibTeX or CSL JSON in your browser, with the field mapping shown and a warning for every record that did not convert cleanly.
NBIB Converter
Convert PubMed .nbib and MEDLINE-format files to RIS, BibTeX or CSL JSON in your browser, with full author names, expanded page ranges, MeSH keywords and retraction warnings.
Check, Tidy and Convert a Reference List
- Check against a style. Checkers for APA 7, MLA 9, Chicago, Harvard, IEEE, Vancouver and AMA, plus a Citation Style Identifier for a list whose style you do not know. The Et Al. Rules Calculator settles how many authors each style lists.
- Tidy and order. The Bibliography Alphabetizer, Duplicate Citation Finder, Numbered Citation Order Checker, Reference Age Checker, Author Name Formatter and Call Number Sorter for Library of Congress and Dewey shelf order.
- BibTeX and LaTeX. DOI to BibTeX, PubMed to BibTeX and URL to BibTeX build entries from an identifier; the BibTeX Cleaner & Validator and BibTeX Key Generator make a .bib file consistent before you compile.
- Reference-manager files. The BibTeX to RIS and RIS to BibTeX converters move between file formats, the Citation Style Converter rewrites a reference list from one style to another, the NBIB Converter turns PubMed exports into RIS, BibTeX or CSL JSON, the EndNote XML Converter does the same for EndNote, the RIS File Validator finds the broken record in an import, and the BibTeX to Word Source Manager Converter feeds Word's citation tool.
- Whole papers. The Reference Extractor pulls the reference list and every in-text citation out of a Word file, and the Citation Counter counts them.
Identifiers, Integrity and Finding Sources
| Task | Tool |
|---|---|
| Add missing DOIs to a reference list | DOI Finder, then DOI Link Formatter to write them the way your style wants |
| Check that a DOI works | DOI Validator & Resolver |
| Convert or validate an ISBN or ISSN | ISBN Converter, ISBN Barcode Generator, ISSN Validator |
| Make sure you are not citing a retracted paper | Retraction Checker |
| Shorten journal titles for Vancouver, AMA or IEEE | Journal Abbreviation Finder |
| Judge a journal before citing or submitting | Journal Metrics Lookup |
| Find a free full-text version | Open Access Finder |
| Follow citations forward and backward from key papers | Citation Chaser |
| Build a PubMed search from controlled vocabulary | MeSH Term Finder |
| List an author's publications | ORCID Publication List Generator |
| Credit a Creative Commons image or text | Creative Commons Attribution Generator |
What a Checker Can and Cannot Tell You
The citation checkers read each entry for patterns a style forbids — an inverted second author in MLA, a missing DOI prefix in APA, a title in the wrong case — and flag likely problems with the reason. They cannot see the source, so they cannot tell you that a year, a volume number or a page range is wrong. Treat a clean result as "nothing looked out of place", not as proof the list is correct.
A tool that looks something up says on its page what it sends and where — the DOI Finder and the Retraction Checker query Crossref, the Open Access Finder, Citation Chaser and Journal Metrics Lookup query OpenAlex, and the ORCID Publication List Generator reads the public ORCID record. The style checkers and file converters work on the text you paste without sending it anywhere. For generating references rather than checking them, see the Citation Generators shelf.
Frequently Asked Questions
- How do I check my reference list for mistakes?
- Paste the list into the checker for your style — APA 7, MLA 9, Chicago or another. Each flagged entry comes with the rule it appears to break. Fix those, then compare a few entries against the sources themselves, since no checker can see a wrong page number.
- How do I convert a DOI to BibTeX?
- Paste one or more DOIs into the DOI to BibTeX Converter. It reads the registered metadata from Crossref and returns a complete @article entry you can paste into your .bib file. Run the file through the BibTeX Cleaner & Validator before you compile.
- How can I tell whether a paper has been retracted?
- Paste the DOIs or the whole reference list into the Retraction Checker. It checks each DOI in Crossref, which includes the Retraction Watch database, and reports retractions, expressions of concern, corrections and withdrawals. A paper without a DOI has to be checked on the publisher's page.
- How do I import a PubMed or EndNote export into another reference manager?
- Export the records from PubMed as a .nbib file or from EndNote as XML, then paste or upload them into the NBIB Converter or EndNote XML Converter and choose RIS, BibTeX or CSL JSON, which nearly every manager reads. Anything that did not map cleanly is listed as a warning so you can fix it by hand.
- When do I use et al. in a citation?
- It depends on the style: APA 7 uses et al. from three authors in the text and lists up to 20 in the reference list, MLA 9 uses it from three authors, and Chicago 18 lists up to six authors in the bibliography. The Et Al. Rules Calculator applies the rule for the style you pick, with a worked example.
- What is the difference between this shelf and the citation generators?
- The citation generators create a reference from a source. These tools work on references you already have — checking, converting, sorting and finding identifiers for them. Nothing here is written back to your document or reference manager: the tools produce a copy for you to review and paste.