Remove duplicate citations from RIS, BibTeX & plain-text references
Your consolidated, deduplicated reference set will appear here.
1. Input data:paste citations in RIS, BibTeX, APA or Vancouver format, or upload a .ris / .bib / .txt / .csv file. Separate entries with a blank line.
2. Matching:the tool runs exact checks on DOI, PubMed ID and year, plus fuzzy title matching using character-distance similarity.
3. Review clusters:each duplicate set is shown side by side with its match confidence; click the entry you want to keep.
4. Export:choose a batch rule or pick manually, then copy or download your clean, duplicate-free reference set.
Tip: turn on DOI and PubMed ID matching for exact duplicates, and raise the fuzzy sensitivity if near-identical titles slip through. Everything runs in your browser — your references are never uploaded.
A reference deduplicator is a free tool that scans a list of citations and removes duplicates — the same source appearing more than once because you searched several databases or exported from different reference managers. It compares entries by DOI, PubMed ID, publication year and title similarity, groups the matches into clusters, and gives you one clean, duplicate-free reference list.
It’s built for researchers running a systematic review or meta-analysis, where searching PubMed, Scopus, Embase and Web of Science routinely produces 30–40% duplicate records that must be removed before screening. It also helps anyone tidying a messy bibliography. Everything happens locally in your browser, so your references are never uploaded or stored.
Deduplication works by matching records on the fields that reliably identify the same source, then letting you decide which copy to keep. This tool uses four signals.
A Digital Object Identifier is unique to each published article, so two records with the same DOI are almost always the same source. DOI matching catches duplicates even when the titles are formatted differently.
For biomedical literature, a shared PMID is another exact identifier. It’s especially useful when DOIs are missing from older or non-indexed records.
Many duplicates have no shared ID — one export abbreviates the journal, another drops a subtitle, a third changes punctuation. Fuzzy matching compares title similarity using character-distance scoring and flags near-identical titles (optionally requiring the same year), so “a meta-analysis” and “a meta analysis” are caught.
Each duplicate cluster is shown side by side. Keep the first entry, apply a rule (most complete metadata, or newest year), or pick manually — then export your clean set.
Removing duplicates is a required, reportable step in systematic review methodology — and getting it wrong distorts your whole review.
Multi-database searches overlap heavily, so a raw export is full of the same studies repeated. If duplicates aren’t removed, you screen the same record several times, waste reviewer effort, and risk counting one study as several — inflating your results. PRISMA 2020 asks you to report exactly how many records were identified and how many duplicates were removed before screening, so a clean, auditable count matters. Deduplicate first, record the numbers, then move the totals straight into your flow diagram.
| Input format | Typical source | Matched on |
|---|---|---|
| RIS (.ris) | EndNote, Zotero, Mendeley, PubMed, Scopus exports | DOI, PMID, title, year |
| BibTeX (.bib) | LaTeX, Google Scholar, Zotero | DOI, title, year |
| Plain text | APA, Vancouver, Harvard reference lists | Title, year, DOI (if present) |
| CSV (.csv) | Spreadsheet exports of references | Title, year, DOI |
Paste entries directly or upload a file. Separate each reference with a blank line for the most accurate parsing.
Catches both identical records (DOI, PMID) and near-duplicates with slightly different titles.
See each duplicate cluster together and choose which version to keep — nothing is deleted blindly.
Handles RIS, BibTeX, plain-text and CSV in one place — even mixed together.
Instantly see total loaded, duplicates found, unique count and your duplication rate.
Download your clean list or copy it to the clipboard, ready for screening or your bibliography.
No sign-up, no cost, and nothing you paste or upload leaves your browser.
| Feature | What it does for you |
|---|---|
| Four matching rules | Toggle DOI, title, PubMed ID and year matching on or off. |
| Adjustable fuzzy sensitivity | Slide from loose (50%) to strict (100%) title similarity. |
| Duplicate clusters | Groups matches with a confidence score for side-by-side review. |
| Batch resolution rules | Keep first, keep most complete, or keep newest across all clusters. |
| Live metrics | Total, duplicates, unique count and duplication rate. |
| Search & copy | Filter the clean list and copy or export it in one click. |
| Paste or upload | Works with pasted text or .ris / .bib / .txt / .csv files. |
| Client-side privacy | All processing runs in your browser — nothing is uploaded. |
Different articles can share similar titles. Use DOI and PMID matching for exact identification wherever possible.
A loose threshold merges distinct papers. Start around 85% and only loosen it if real duplicates are missed.
Always check which copy you keep — the most complete record (with DOI, PMID, full authors) is usually best.
PRISMA requires the count of duplicates removed. Note your duplication stats before moving on.
Separate each reference with a blank line so the parser reads them as distinct records.
Remove duplicate records from multi-database searches before screening.
Ensure each study is counted once across overlapping database exports.
Clean up a long bibliography built from many search sessions.
De-duplicate an EndNote, Zotero or Mendeley library export.
Consolidate sources from different databases into one clean list.
Produce a tidy, duplicate-free reference section fast.
Paste or upload your references, choose your matching rules (DOI, PubMed ID, title and year), and click “Find & process duplicates”. The tool groups duplicates into clusters so you can keep the best copy of each, then copy or export your clean, deduplicated list.
RIS (.ris), BibTeX (.bib), plain-text citations (APA, Vancouver, Harvard) and CSV. You can paste entries directly or upload a file, and it even handles a mix of formats in one list.
It compares the similarity of two titles using character-distance scoring and flags pairs above your chosen threshold. This catches near-duplicates with small differences — abbreviated journals, dropped subtitles, or punctuation changes — that an exact match would miss. You can require the same publication year as well.
Exact matching on DOI and PubMed ID is highly reliable, and the review step lets you confirm every fuzzy match before anything is removed. For a formal review, always check the clusters manually and record the number of duplicates removed for your PRISMA report.
Yes. Export your library as RIS or BibTeX and paste or upload it here. You can then import the cleaned list back into your reference manager.
Completely. All matching and deduplication happens locally in your browser using JavaScript. Nothing you paste or upload is sent to any server, so it’s safe for unpublished work.
It varies, but searching several databases commonly produces 20–40% duplicate records once overlapping results are combined. The tool shows your exact duplication rate so you can report it.
Yes. For support with screening, synthesis and editing, see ManuscriptLab’s scientific editing service, and build your flow diagram with our free PRISMA generator.
This Reference Deduplicator processes your citations locally in your browser to find and remove duplicates. Always review each cluster before removing records, keep a copy of your original file, and record the number of duplicates removed for your PRISMA report. Need help with the full review? Explore our scientific editing service or the free PRISMA flow diagram generator.
Deduplication is one step — if you’d like support with screening, data extraction, statistical synthesis, or editing your review for submission, our team does exactly that. Real human editors and methodologists, matched to your field.
Tell us a bit about your project and we’ll get back to you within 24 hours.