Paste BibTeX and remove duplicates matched by normalised title or DOI, keeping the fuller entry. Free, no sign-up.
What this tool does
Reference managers collect duplicates: the same paper imported from two databases, once with a DOI and once without, once with a capitalised title and once without. Sorting them by hand in a 300-entry library is miserable. This tool normalises titles (lowercase, punctuation stripped) and DOIs, groups entries that match on either, and keeps the fuller entry from each group — so your .bib file shrinks without losing information.
Why it matters
Good citations do quiet work. They let a reader find every source you used, they show that your argument rests on real evidence rather than memory, and they protect you: a clean reference list is much harder to challenge than a vague one. Most marks lost on referencing are not lost on difficult sources. They are lost on small, repeated slips — a missing year, a swapped initial, a title in the wrong case — that a quick tool pass catches before submission.
How to use it
- Paste your BibTeX entries.
- Click Merge duplicates.
- Copy the deduplicated BibTeX.
Worked example
Two entries for the same paper — one titled ‘Clean Water Systems’ with a DOI, one titled ‘clean water systems.’ without — merge into one entry: the DOI version wins because it is fuller. The tool reports ‘2 entries in, 1 out, 1 duplicate removed.’
Tips for good results
Back up your .bib file before merging. Dedupe is easy to redo; an overwritten library is not.
Work from the source itself, not from another paper’s copy of it. And keep one style for the whole list: a single mixed entry undermines an otherwise perfect bibliography.
Honest limits
Matching is by normalised title or exact DOI. Near-duplicates with different titles (a preprint title vs the published title) will not merge, and two genuinely different papers with identical titles would merge — check the report line before replacing your library file.
Common mistakes to avoid
Common mistakes to avoid: copying a reference from another paper without checking it against the original, trusting a PDF filename for the title or year, and mixing two styles in one list. Each of these looks harmless alone and careless together. Run the tool, read its output once, and compare it with the source itself before you paste it into your document.
Before you submit
Run through this short check before you submit: is every author name spelled as it appears on the source, is every year present and correct, and does every in-text citation have a matching entry in your reference list? Read the list once from top to bottom rather than skimming it. Most referencing errors are found in that single slow read, and fixing them there is far cheaper than fixing them after a reviewer finds them. If one entry still looks odd after that read, check it against the original source before you change anything else.
Frequently asked questions
Is this tool really free?
Yes. It runs in your browser on this page, with no account and no payment. Nothing you paste leaves your computer.
Do I still need to check the result?
Yes, once. Tools apply rules; they cannot verify facts about your source. Compare the output with the source itself before submitting.
Can I use the output in my paper?
Yes. The output is a formatted reference or analysis for your own work. Keep the source’s facts accurate and the formatting consistent across your list.
What if the tool’s output differs from my style guide?
Trust the style guide. Tools encode the common rules of a style; your university or journal’s own sheet wins every disagreement. Use the tool to do the routine work, then apply the local rule where it differs.
Also available in Spanish: Fusionador de Referencias Duplicadas – Elimina Duplicados BibTeX por Título y DOI Gratis.