What is the BIBTEX file format?
.bibtex is a non-standard extension variant of the canonical .bib bibliography database format used with LaTeX typesetting systems. The format was created by Oren Patashnik and Leslie Lamport in 1985 and stores academic reference entries as plain text using @-prefixed entry types.
Each entry follows the pattern @type{citekey, field = {value}, ...}, where type is one of @article, @book, @inproceedings, @misc, and so on. The file may also contain @string macro definitions and @comment blocks. There are no binary signatures - the content is indistinguishable from a standard .bib file.
The .bibtex extension is not historically standardized; it emerged in text editor ecosystems (notably Sublime Text, which uses it for syntax-highlighting association) and as an export convention in some reference managers. Because most LaTeX tools - including BibTeX 0.99d, BibLaTeX, and reference managers such as JabRef and Zotero - expect the .bib extension, a file saved as .bibtex may need to be renamed to .bib before the toolchain recognizes it.
Encoding is plain ASCII or UTF-8; older files often use LaTeX escape sequences such as {\'e} for accented characters instead of raw Unicode. BibLaTeX and Biber modernize the bibliography pipeline and add richer entry types, but the underlying file format remains the same.
Security & safety
RISK: LOWPlain-text metadata about publications - no code, no macros, no execution risk. Safe to open in any text editor. A url/doi field could point anywhere but managers do not auto-open them. Malformed entries will break a LaTeX build but cannot harm the system.
Format details
in a nutshellPrograms that open BIBTEX files
Windows4 apps
Sublime Text
Freemium Opens .bibtex natively with BibTeX syntax highlighting (it is one of Sublime's own supported extensions). Use for editing the raw text. 
JabRef
Open-source Rename .bibtex to .bib, then open in JabRef - purpose-built BibTeX manager with table editor. 
Zotero
Open-source Rename .bibtex to .bib, then File > Import. Free reference manager with great Overleaf integration.
Notepad / any text editor
Built-in It is plain text - open in Notepad to read or quickly edit an entry. No rename needed. 
macOS2 apps
Linux1 app
Overleaf
Freemium Rename .bibtex to .bib, upload to your Overleaf LaTeX project, and reference with \bibliography{}. Technical details
deep spec| Format type | Plain-text BibTeX bibliography database |
| Entry syntax | `@type{citekey, field = {value}, ...}` - e.g. `@article{`, `@book{` |
| MIME type | `text/x-bibtex`; also recognized as `application/x-bibtex` or `text/plain` |
| Relation to .bib | Functionally identical to `.bib`; `.bibtex` is a non-standard variant of the canonical `.bib` extension |
| Text encoding | ASCII or UTF-8; legacy files use LaTeX escape sequences for accented characters |
| Supported entry types | `@article`, `@book`, `@inproceedings`, `@phdthesis`, `@misc`, `@techreport`, and others; BibLaTeX adds further types |
| Macro support | `@string` blocks define reusable abbreviations; `@comment` blocks are ignored by the BibTeX processor |
| File size range | Typically 1 KB to a few MB (a handful to tens of thousands of references) |
| Cite-key | Each entry has a unique cite-key referenced in LaTeX `\cite{}` commands |
| Required vs optional fields | Each entry type defines required and optional fields (e.g. `@article` requires `author`, `title`, `journal`, `year`) |
| BibLaTeX compatibility | BibLaTeX/Biber extend the toolchain with additional entry/field types but use the same plain-text file format |
| Tool compatibility | Most BibTeX tools expect `.bib`; rename `.bibtex` to `.bib` if the tool does not recognize the longer extension |
| Released | 1985 (BibTeX 0.98); .bibtex extension non-standard, used occasionally by editors/export tools |
| Latest version | BibTeX 0.99d (2010); BibLaTeX modernizes the toolchain but uses the same file format |
| Open standard | Yes · royalty-free |
| Specification | www.bibtex.org |
BIBTEX conversions
Community Q&A
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