Overleaf: How to Download the .bbl File

A .bbl file is an auxiliary file normally generated by a bibliography processor such as BibTeX or Biber. It contains the formatted bibliography entries that LaTeX reads when producing the PDF. It is not normally one of the source files you write by hand.

On Overleaf, compile the project first, then download the file from the generated output files rather than from the main file list.

Download the generated .bbl file

1. Open the project in Overleaf.
2. Click Recompile. If necessary, compile more than once so that citations and references are fully updated.
3. Open Logs and output files. Depending on the Overleaf interface, this button may appear beside the Recompile button or in the compile-output panel.
4. Expand Other logs and files.
5. Locate the file with the same base name as your main TeX file. For example, if the main file is paper.tex, the generated file is usually paper.bbl.
6. Click the download icon or the file name to save it.

The .bbl file is generated in the project’s compilation output. It may not appear in the ordinary source-file tree because it is a derived file rather than an uploaded project source.

Minimal example using BibTeX

If the first snippet is saved as main.tex, it creates a .bbl file named main.bbl after a successful BibTeX compilation:

\documentclass{article}

\begin{document}

A citation appears here: \cite{knuth1984}.

\bibliographystyle{plain}
\bibliography{references}

\end{document}

Create a second project file named references.bib:

@book{knuth1984,
  author    = {Donald E. Knuth},
  title     = {The TeXbook},
  publisher = {Addison-Wesley},
  year      = {1984}
}

After compiling, the usual sequence is conceptually:

pdflatex main
bibtex main
pdflatex main
pdflatex main

Overleaf normally runs the required compilation steps automatically. The first LaTeX run writes citation information to main.aux; BibTeX reads that information and references.bib, then writes main.bbl; later LaTeX runs read main.bbl and resolve the citations.

If you use biblatex and Biber

A project using biblatex often uses Biber instead of traditional BibTeX:

\documentclass{article}
\usepackage[backend=biber]{biblatex}
\addbibresource{references.bib}

\begin{document}

A citation appears here: \cite{knuth1984}.

\printbibliography

\end{document}

For this version, Overleaf must run Biber, not BibTeX. The generated .bbl file is still available among the output files, but its contents and the auxiliary files involved differ from a traditional BibTeX project.

Do not switch between BibTeX and Biber casually. The backend should match the backend option in biblatex; otherwise the bibliography may remain empty or compilation may report that no bibliography was produced.

Why the .bbl file might be missing

The bibliography has not been processed

A .bbl file is not created merely because a .bib file exists. Compile the project and ensure that the bibliography tool runs successfully. After a failed run, there may be no new .bbl file, although an older generated file can remain.

The main file is different from the file you expect

The output name normally follows the main document. If the project’s main file is thesis.tex, look for thesis.bbl, not necessarily main.bbl.

There is a BibTeX or Biber error

Open the compilation log and look for messages such as an undefined citation key, a missing .bib file, malformed BibTeX syntax, or a missing bibliography style. Correct the error and recompile.

The bibliography is empty

Check that every citation key in \cite{...} exactly matches a key in the .bib file. With traditional BibTeX, also check that \bibliography{...} and \bibliographystyle{...} occur in the document. With biblatex, use \addbibresource{...} and \printbibliography.

The file is hidden among auxiliary files

Generated files are commonly placed under Other logs and files, not beside the .tex and .bib files. If the interface has a filtered output list, search for bbl or scroll through the auxiliary files.

Downloading a complete project versus downloading only .bbl

Use the output-file panel when you need only the generated bibliography. If you download the project source as a ZIP archive, Overleaf may distinguish between editable source files and generated compilation files; therefore, do not assume that the source ZIP contains every auxiliary file. Download the .bbl explicitly from the compilation output when a journal, collaborator, or submission system requests it.

A .bbl file is tied to the document’s bibliography setup and the bibliography tool that produced it. If you send it to someone else, include the corresponding .tex file and explain whether it was produced by BibTeX or Biber. Rebuilding the document may require the .bib database, bibliography style, package files, and matching compiler settings.