BibTeX Reference Deduplicator

Scan your bibliography for duplicate entries caused by merging multiple libraries. Resolves conflicts locally without uploading your research data.

1. Input Bibliography

2. Resolve Conflicts

Upload a library to scan for duplicate citations.

How-To Guide

How to de-duplicate a BibTeX library

Merging reference libraries almost always creates duplicate citations. Here is the fastest way to find and remove them without uploading your research data.

1

Add your library

Paste BibTeX entries into the input box, or click Upload .bib to load a file. Merged exports from Zotero, Mendeley or EndNote are ideal candidates.

2

Scan for duplicates

Press Scan for Duplicates. Entries are matched by DOI first, then by a normalized title, and grouped into conflicts.

3

Resolve each conflict

For every group, click Keep This Entry on the version you want to retain, or use Auto-Keep First to keep the earliest copy of each.

4

Export the clean file

Once all conflicts are resolved, click Export Cleaned .bib to download a de-duplicated bibliography with the original entry order preserved.

How the deduplicator works

Two-stage matching

A DOI is a globally unique identifier, so two entries sharing one (after lower-casing and stripping any doi.org prefix) are treated as the same work. Entries are also merged when their normalized titles match, lower-cased, with LaTeX braces, commands, math and punctuation removed. This catches duplicates where one copy is missing its DOI, a common result of merging databases.

Transitive grouping & privacy

Matches are combined with a union-find structure, so a chain such as A(doi)=B(title)=C collapses into a single conflict. Nothing is auto-merged field-by-field, you choose which record survives. All parsing happens locally in your browser; your library is never uploaded.

Frequently asked questions

Is my bibliography uploaded to a server?
No. Parsing and de-duplication run entirely in your browser using client-side JavaScript. Your .bib data never leaves your device.
How are duplicates detected?
By DOI first (the most reliable signal), then by a normalized title comparison. Matches are grouped transitively, so overlapping DOI and title links are collapsed into one conflict.
Will it automatically merge fields from both copies?
No. The tool never silently combines records. For each conflict you keep exactly one entry, so you stay in control of which metadata is retained.
Why were two different papers flagged as duplicates?
They likely share an identical normalized title (for example, generic titles like ‘Introduction’). Review the conflict and keep both by choosing one, then re-adding the other if needed. DOIs prevent most false matches.
What input does it accept?
Standard BibTeX (.bib) entries such as @article, @inproceedings and @book. String macros and comments are ignored during matching.
About the DOI system Overleaf: BibTeX guide

Runs entirely in your browser, no data leaves your device.