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cffr

cffr provides utilities to generate, coerce, modify, and validate CITATION.cff files automatically for R packages, along with tools and examples for working with .cff files more generally.

What is a CITATION.cff file?

Citation File Format (CFF) (Druskat et al. 2021) (v1.2.0) are plain text files with human- and machine-readable citation information for software (and datasets). Code developers can include them in their repositories to let others know how to correctly cite their software.

This format is gaining popularity within the software citation ecosystem. Recently, GitHub, Zenodo, and Zotero have fully supported this citation format (Druskat 2021). GitHub support is of special interest:

Tweet of Nat Friedman about CFF files

— Nat Friedman (@natfriedman) July 27, 2021

See Enhanced support for citations on GitHub (Smith 2021) for more information.

The CodeMeta Project (Jones et al. 2017) creates a concept vocabulary that can be used to standardize the exchange of software metadata across repositories and organizations. One of the many uses of a codemeta.json file (created following the standards defined by The CodeMeta Project) is to provide citation metadata such as title, authors, publication year, and venue (Fenner 2021). The packages codemeta (Boettiger and Salmon 2021a) and codemetar (Boettiger and Salmon 2021b) allow for generating codemeta.json files from R package metadata.

The cffr package

cffr maximizes data extraction by utilizing both the DESCRIPTION file and the CITATION file (if present) from your package. Note that cffr works best if your package passes R CMD check/devtools::check().

As per 2026-02-15 there are at least 470 repos on GitHub using cffr. Check them out here.

Installation

Install cffr from CRAN:

You can install the developing version of cffr with:

remotes::install_github("ropensci/cffr")

Alternatively, you can install cffr using the r-universe:

# Install cffr in R:
install.packages(
  "cffr",
  repos = c("https://ropensci.r-universe.dev", "https://cloud.r-project.org")
)

Example

Most commonly, from within your package folder, you’ll simply run cff_write(), which creates a cff object, writes it to a CITATION.cff file, and validates it in a single command:

library(cffr)

# For in-development packages
cff_write()
#>
#> CITATION.cff generated
#>
#> cff_validate results-----
#> Congratulations! This .cff file is valid

However, cffr provides also custom print methods and mechanisms that allows you to customize the CITATION.cff and integrate them in your workflows.

This is a basic example which shows you how to create a cff object (see ?cff for more info). In this case, we are creating a cff object from the metadata of the rmarkdown package:

library(cffr)

# Example with an installed package
test <- cff_create("knitr")
CITATION.cff for knitr 
cff-version: 1.2.0
message: 'To cite package "knitr" in publications use:'
type: software
license: GPL-1.0-only
title: 'knitr: A General-Purpose Package for Dynamic Report Generation in R'
version: '1.51'
identifiers:
- type: doi
  value: 10.32614/CRAN.package.knitr
abstract: Provides a general-purpose tool for dynamic report generation in R using
  Literate Programming techniques.
authors:
- family-names: Xie
  given-names: Yihui
  email: xie@yihui.name
  orcid: https://orcid.org/0000-0003-0645-5666
preferred-citation:
  type: manual
  title: 'knitr: A General-Purpose Package for Dynamic Report Generation in R'
  authors:
  - family-names: Xie
    given-names: Yihui
    orcid: https://orcid.org/0000-0003-0645-5666
    email: xie@yihui.name
  year: '2025'
  notes: R package version 1.51
  url: https://yihui.org/knitr/
repository: https://CRAN.R-project.org/package=knitr
repository-code: https://github.com/yihui/knitr
commit: '1.51'
url: https://yihui.org/knitr/
date-released: '2025-12-20'
contact:
- family-names: Xie
  given-names: Yihui
  email: xie@yihui.name
  orcid: https://orcid.org/0000-0003-0645-5666
keywords:
- dynamic-documents
- knitr
- literate-programming
- r
- r-package
- rmarkdown
- sweave
references:
- type: book
  title: Dynamic Documents with R and knitr
  authors:
  - family-names: Xie
    given-names: Yihui
  publisher:
    name: Chapman and Hall/CRC
    address: Boca Raton, Florida
  year: '2015'
  edition: 2nd
  notes: ISBN 978-1498716963
  url: https://yihui.org/knitr/
- type: generic
  title: 'knitr: A Comprehensive Tool for Reproducible Research in R'
  authors:
  - family-names: Xie
    given-names: Yihui
  collection-title: Implementing Reproducible Computational Research
  collection-type: collection
  editors:
  - family-names: Stodden
    given-names: Victoria
  - family-names: Leisch
    given-names: Friedrich
  - family-names: Peng
    given-names: Roger D.
  publisher:
    name: Chapman and Hall/CRC
  year: '2014'
  notes: ISBN 978-1466561595
- type: software
  title: 'R: A Language and Environment for Statistical Computing'
  notes: Depends
  url: https://www.R-project.org/
  authors:
  - name: R Core Team
  institution:
    name: R Foundation for Statistical Computing
    address: Vienna, Austria
  year: '2026'
  version: '>= 3.6.0'
- type: software
  title: evaluate
  abstract: 'evaluate: Parsing and Evaluation Tools that Provide More Details than
    the Default'
  notes: Imports
  url: https://evaluate.r-lib.org/
  repository: https://CRAN.R-project.org/package=evaluate
  authors:
  - family-names: Wickham
    given-names: Hadley
    email: hadley@posit.co
  - family-names: Xie
    given-names: Yihui
    orcid: https://orcid.org/0000-0003-0645-5666
  year: '2026'
  doi: 10.32614/CRAN.package.evaluate
  version: '>= 0.15'
- type: software
  title: highr
  abstract: 'highr: Syntax Highlighting for R Source Code'
  notes: Imports
  url: https://github.com/yihui/highr
  repository: https://CRAN.R-project.org/package=highr
  authors:
  - family-names: Xie
    given-names: Yihui
    email: xie@yihui.name
    orcid: https://orcid.org/0000-0003-0645-5666
  - family-names: Qiu
    given-names: Yixuan
  year: '2026'
  doi: 10.32614/CRAN.package.highr
  version: '>= 0.11'
- type: software
  title: methods
  abstract: 'R: A Language and Environment for Statistical Computing'
  notes: Imports
  authors:
  - name: R Core Team
  institution:
    name: R Foundation for Statistical Computing
    address: Vienna, Austria
  year: '2026'
- type: software
  title: tools
  abstract: 'R: A Language and Environment for Statistical Computing'
  notes: Imports
  authors:
  - name: R Core Team
  institution:
    name: R Foundation for Statistical Computing
    address: Vienna, Austria
  year: '2026'
- type: software
  title: xfun
  abstract: 'xfun: Supporting Functions for Packages Maintained by ''Yihui Xie'''
  notes: Imports
  url: https://github.com/yihui/xfun
  repository: https://CRAN.R-project.org/package=xfun
  authors:
  - family-names: Xie
    given-names: Yihui
    email: xie@yihui.name
    orcid: https://orcid.org/0000-0003-0645-5666
  year: '2026'
  doi: 10.32614/CRAN.package.xfun
  version: '>= 0.52'
- type: software
  title: yaml
  abstract: 'yaml: Methods to Convert R Data to YAML and Back'
  notes: Imports
  url: https://yaml.r-lib.org
  repository: https://CRAN.R-project.org/package=yaml
  authors:
  - family-names: Stephens
    given-names: Jeremy
  - family-names: Simonov
    given-names: Kirill
  year: '2026'
  doi: 10.32614/CRAN.package.yaml
  version: '>= 2.1.19'
- type: software
  title: bslib
  abstract: 'bslib: Custom ''Bootstrap'' ''Sass'' Themes for ''shiny'' and ''rmarkdown'''
  notes: Suggests
  url: https://rstudio.github.io/bslib/
  repository: https://CRAN.R-project.org/package=bslib
  authors:
  - family-names: Sievert
    given-names: Carson
    email: carson@posit.co
    orcid: https://orcid.org/0000-0002-4958-2844
  - family-names: Cheng
    given-names: Joe
    email: joe@posit.co
  - family-names: Aden-Buie
    given-names: Garrick
    email: garrick@posit.co
    orcid: https://orcid.org/0000-0002-7111-0077
  year: '2026'
  doi: 10.32614/CRAN.package.bslib
- type: software
  title: DBI
  abstract: 'DBI: R Database Interface'
  notes: Suggests
  url: https://dbi.r-dbi.org
  repository: https://CRAN.R-project.org/package=DBI
  authors:
  - name: R Special Interest Group on Databases (R-SIG-DB)
  - family-names: Wickham
    given-names: Hadley
  - family-names: Müller
    given-names: Kirill
    email: kirill@cynkra.com
    orcid: https://orcid.org/0000-0002-1416-3412
  year: '2026'
  doi: 10.32614/CRAN.package.DBI
  version: '>= 0.4-1'
- type: software
  title: digest
  abstract: 'digest: Create Compact Hash Digests of R Objects'
  notes: Suggests
  url: https://eddelbuettel.github.io/digest/
  repository: https://CRAN.R-project.org/package=digest
  authors:
  - family-names: Eddelbuettel
    given-names: Dirk
    email: edd@debian.org
    orcid: https://orcid.org/0000-0001-6419-907X
  year: '2026'
  doi: 10.32614/CRAN.package.digest
- type: software
  title: htmlwidgets
  abstract: 'htmlwidgets: HTML Widgets for R'
  notes: Suggests
  url: https://github.com/ramnathv/htmlwidgets
  repository: https://CRAN.R-project.org/package=htmlwidgets
  authors:
  - family-names: Vaidyanathan
    given-names: Ramnath
  - family-names: Xie
    given-names: Yihui
  - family-names: Allaire
    given-names: JJ
  - family-names: Cheng
    given-names: Joe
    email: joe@posit.co
  - family-names: Sievert
    given-names: Carson
    email: carson@posit.co
    orcid: https://orcid.org/0000-0002-4958-2844
  - family-names: Russell
    given-names: Kenton
  year: '2026'
  doi: 10.32614/CRAN.package.htmlwidgets
  version: '>= 0.7'
- type: software
  title: otel
  abstract: 'otel: OpenTelemetry R API'
  notes: Suggests
  url: https://otel.r-lib.org
  repository: https://CRAN.R-project.org/package=otel
  authors:
  - family-names: Csárdi
    given-names: Gábor
    email: csardi.gabor@gmail.com
  year: '2026'
  doi: 10.32614/CRAN.package.otel
- type: software
  title: ragg
  abstract: 'ragg: Graphic Devices Based on AGG'
  notes: Suggests
  url: https://ragg.r-lib.org
  repository: https://CRAN.R-project.org/package=ragg
  authors:
  - family-names: Pedersen
    given-names: Thomas Lin
    email: thomas.pedersen@posit.co
    orcid: https://orcid.org/0000-0002-5147-4711
  - family-names: Shemanarev
    given-names: Maxim
  year: '2026'
  doi: 10.32614/CRAN.package.ragg
- type: software
  title: rlang
  abstract: 'rlang: Functions for Base Types and Core R and ''Tidyverse'' Features'
  notes: Suggests
  url: https://rlang.r-lib.org
  repository: https://CRAN.R-project.org/package=rlang
  authors:
  - family-names: Henry
    given-names: Lionel
    email: lionel@posit.co
  - family-names: Wickham
    given-names: Hadley
    email: hadley@posit.co
  year: '2026'
  doi: 10.32614/CRAN.package.rlang
- type: software
  title: rmarkdown
  abstract: 'rmarkdown: Dynamic Documents for R'
  notes: Suggests
  url: https://pkgs.rstudio.com/rmarkdown/
  repository: https://CRAN.R-project.org/package=rmarkdown
  authors:
  - family-names: Allaire
    given-names: JJ
    email: jj@posit.co
  - family-names: Xie
    given-names: Yihui
    email: xie@yihui.name
    orcid: https://orcid.org/0000-0003-0645-5666
  - family-names: Dervieux
    given-names: Christophe
    email: cderv@posit.co
    orcid: https://orcid.org/0000-0003-4474-2498
  - family-names: McPherson
    given-names: Jonathan
    email: jonathan@posit.co
  - family-names: Luraschi
    given-names: Javier
  - family-names: Ushey
    given-names: Kevin
    email: kevin@posit.co
  - family-names: Atkins
    given-names: Aron
    email: aron@posit.co
  - family-names: Wickham
    given-names: Hadley
    email: hadley@posit.co
  - family-names: Cheng
    given-names: Joe
    email: joe@posit.co
  - family-names: Chang
    given-names: Winston
    email: winston@posit.co
  - family-names: Iannone
    given-names: Richard
    email: rich@posit.co
    orcid: https://orcid.org/0000-0003-3925-190X
  year: '2026'
  doi: 10.32614/CRAN.package.rmarkdown
- type: software
  title: sass
  abstract: 'sass: Syntactically Awesome Style Sheets (''Sass'')'
  notes: Suggests
  url: https://rstudio.github.io/sass/
  repository: https://CRAN.R-project.org/package=sass
  authors:
  - family-names: Cheng
    given-names: Joe
    email: joe@rstudio.com
  - family-names: Mastny
    given-names: Timothy
    email: tim.mastny@gmail.com
  - family-names: Iannone
    given-names: Richard
    email: rich@rstudio.com
    orcid: https://orcid.org/0000-0003-3925-190X
  - family-names: Schloerke
    given-names: Barret
    email: barret@rstudio.com
    orcid: https://orcid.org/0000-0001-9986-114X
  - family-names: Sievert
    given-names: Carson
    email: carson@rstudio.com
    orcid: https://orcid.org/0000-0002-4958-2844
  year: '2026'
  doi: 10.32614/CRAN.package.sass
- type: software
  title: styler
  abstract: 'styler: Non-Invasive Pretty Printing of R Code'
  notes: Suggests
  url: https://styler.r-lib.org
  repository: https://CRAN.R-project.org/package=styler
  authors:
  - family-names: Müller
    given-names: Kirill
    email: kirill@cynkra.com
    orcid: https://orcid.org/0000-0002-1416-3412
  - family-names: Walthert
    given-names: Lorenz
    email: lorenz.walthert@icloud.com
  - family-names: Patil
    given-names: Indrajeet
    email: patilindrajeet.science@gmail.com
    orcid: https://orcid.org/0000-0003-1995-6531
  year: '2026'
  doi: 10.32614/CRAN.package.styler
  version: '>= 1.2.0'
- type: software
  title: tibble
  abstract: 'tibble: Simple Data Frames'
  notes: Suggests
  url: https://tibble.tidyverse.org/
  repository: https://CRAN.R-project.org/package=tibble
  authors:
  - family-names: Müller
    given-names: Kirill
    email: kirill@cynkra.com
    orcid: https://orcid.org/0000-0002-1416-3412
  - family-names: Wickham
    given-names: Hadley
    email: hadley@rstudio.com
  year: '2026'
  doi: 10.32614/CRAN.package.tibble
- type: software
  title: tinytex
  abstract: 'tinytex: Helper Functions to Install and Maintain TeX Live, and Compile
    LaTeX Documents'
  notes: Suggests
  url: https://github.com/rstudio/tinytex
  repository: https://CRAN.R-project.org/package=tinytex
  authors:
  - family-names: Xie
    given-names: Yihui
    email: xie@yihui.name
    orcid: https://orcid.org/0000-0003-0645-5666
  year: '2026'
  doi: 10.32614/CRAN.package.tinytex
  version: '>= 0.56'
- type: software
  title: rstudioapi
  abstract: 'rstudioapi: Safely Access the RStudio API'
  notes: Suggests
  url: https://rstudio.github.io/rstudioapi/
  repository: https://CRAN.R-project.org/package=rstudioapi
  authors:
  - family-names: Ushey
    given-names: Kevin
    email: kevin@rstudio.com
  - family-names: Allaire
    given-names: JJ
    email: jj@posit.co
  - family-names: Wickham
    given-names: Hadley
    email: hadley@posit.co
  - family-names: Ritchie
    given-names: Gary
    email: gary@posit.co
  year: '2026'
  doi: 10.32614/CRAN.package.rstudioapi

We can validate the result using cff_validate():

cff_validate(test)
#> ══ Validating cff ══════════════════════════════════════════════════════════════

Check the docs and vignette("cffr", package = "cffr") to learn how to work with cff objects.

Keep your CITATION.cff file up-to-date

GitHub Actions

The easiest way to keep your CITATION.cff file up-to-date is using GitHub Actions. Use cff_gha_update() function to install a GitHub Action that will update your CITATION.cff file on the following events:

  • When you publish a new release of the package on your GitHub repo.
  • Each time that you modify your DESCRIPTION or inst/CITATION files.
  • The action can be run also manually.
cff_gha_update()

#> ✔ Installing ./.github/workflows/update-citation-cff.yaml
#> ℹ Adding ".github" to .Rbuildignore

See the example workflow file here.

Git pre-commit hook Experimental

You can also use a git pre-commit hook:

The pre-commit hook is run first, before you even type in a commit message. It’s used to inspect the snapshot that’s about to be committed, to see if you’ve forgotten something, to make sure tests run, or to examine whatever you need to inspect in the code. Exiting non-zero from this hook aborts the need to inspect in the code. Exiting non-zero from this hook aborts the commit, although you can bypass it with git commit --no-verify.

A specific pre-commit hook can be installed with cff_git_hook_install(). If you want to use a pre-commit hook, please make sure you have the testthat package installed.

Learn more

Check the following articles to learn more about cffr:

Code of Conduct

Please note that the cffr project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.

Citation

Hernangómez, D., (2021). cffr: Generate Citation File Format Metadata for R Packages. Journal of Open Source Software, 6(67), 3900, https://doi.org/10.21105/joss.03900

A BibTeX entry for LaTeX users is:

@article{hernangomez2021,
    title        = {{cffr}: Generate Citation File Format Metadata for {R} Packages},
    author       = {Diego Hernangómez},
    year         = 2021,
    journal      = {Journal of Open Source Software},
    publisher    = {The Open Journal},
    volume       = 6,
    number       = 67,
    pages        = 3900,
    doi          = {10.21105/joss.03900},
    url          = {https://doi.org/10.21105/joss.03900}
}

You can also use the citation provided by GitHub, that is generated from the information of a CITATION.cff created with cffr. See About CITATION files for more info.

References

Boettiger, Carl, and Maëlle Salmon. 2021a. codemeta: A Smaller codemetar Package. https://CRAN.R-project.org/package=codemeta.
———. 2021b. codemetar: Generate ’CodeMeta’ Metadata for R Packages.
Chamberlain, Scott, and Brenton M. Wiernik. 2026. handlr: Convert Among Citation Formats. https://doi.org/10.32614/CRAN.package.handlr.
Dietrich, Jan Philipp, and Waldir Leoncio. 2022. citation: Software Citation Tools. https://doi.org/10.32614/CRAN.package.citation.
Druskat, Stephan. 2021. “Making Software Citation Easi(er) - The Citation File Format and Its Integrations.” https://doi.org/10.5281/zenodo.5529914.
Druskat, Stephan, Jurriaan H. Spaaks, Neil Chue Hong, Robert Haines, James Baker, Spencer Bliven, Egon Willighagen, David Pérez-Suárez, and Alexander Konovalov. 2021. “Citation File Format.” https://doi.org/10.5281/zenodo.5171937.
Fenner, Martin. 2021. “We Need Your Feedback: Aligning the CodeMeta Vocabulary for Scientific Software with Schema.org.” https://doi.org/10.5438/a49j-x692.
Jones, Matthew B, Carl Boettiger, Abby Cabunoc Mayes, Arfon Smith, Peter Slaughter, Kyle Niemeyer, Yolanda Gil, et al. 2017. CodeMeta: An Exchange Schema for Software Metadata. KNB Data Repository. https://doi.org/10.5063/SCHEMA/CODEMETA-2.0.
Smith, Arfon. 2021. “Enhanced Support for Citations on GitHub.”https://github.blog/news-insights/company-news/enhanced-support-citations-github/.