ymlthis is now retired: only changes necessary to keep it on CRAN will be made. ymlthis was created when managing YAML in R Markdown was difficult. Quarto has since resolved these issues with autocomplete, validation, and helpful error messages for YAML. We recommend Quarto for new projects. Existing ymlthis code will continue to work, and the package will remain on CRAN.

ymlthis makes it easy to write YAML front matter for R Markdown and related documents. yml_*() functions write functions and use_*() functions let you write the resulting YAML to your clipboard or to .yml files related to your project.

You can install ymlthis from CRAN with:

install.packages("ymlthis")

Or you can install the development version of ymlthis from GitHub with:

# install.packages("remotes")
remotes::install_github("r-lib/ymlthis")

yml() creates a basic yml object returns simple YAML with the author and date.

library(ymlthis)

yml()
#> ---
#> author: Malcolm Barrett
#> date: '`r format(Sys.Date())`'
#> ---

ymlthis supports many YAML arguments, with YAML-generating functions prefixed with yml_*():

yml() %>% 
  yml_author(c("Yihui Xie", "Hadley Wickham"), affiliation = "RStudio") %>% 
  yml_date(lubridate::today()) %>% 
  yml_output(
    word_document(keep_md = TRUE), 
    bookdown::html_document2()
  ) %>% 
  yml_citations(bibliography = "references.bib", csl = "aje.csl")
#> ---
#> author:
#> - name: Yihui Xie
#>   affiliation: RStudio
#> - name: Hadley Wickham
#>   affiliation: RStudio
#> date: '2026-02-16'
#> output:
#>   word_document:
#>     keep_md: true
#>   bookdown::html_document2: default
#> bibliography: references.bib
#> csl: aje.csl
#> ---

ymlthis also includes an add-in that will create YAML for you and put it in a file, such as an .Rmd file, or on your clipboard.