A 'real-time' theme customization UI that you can use to easily make common tweaks to Bootstrap variables and immediately see how they would affect your app's appearance. There are two ways you can launch the theming UI. For most Shiny apps, just use run_with_themer() in place of shiny::runApp(); they should take the same arguments and work the same way. Alternatively, you can call the bs_themer() function from inside your server function (or in an R Markdown app that is using runtime: shiny, you can call this from any code chunk). Note that this function is only intended to be used for development!

run_with_themer(appDir = getwd(), ..., gfonts = TRUE, gfonts_update = FALSE)

bs_themer(gfonts = TRUE, gfonts_update = FALSE)



The application to run. This can be a file or directory path, or a shiny::shinyApp() object. See shiny::runApp() for details.


Additional parameters to pass through to shiny::runApp().


whether or not to detect Google Fonts and wrap them in font_google() (so that their font files are automatically imported).


whether or not to update the internal database of Google Fonts.


nothing. These functions are called for their side-effects.


To help you utilize the changes you see in the preview, this utility prints bs_theme() code to the R console.


  • Doesn't work with Bootstrap 3.

  • Doesn't work with IE11.

  • Only works inside Shiny apps and runtime: shiny R Markdown documents.

    • Can't be used with static R Markdown documents.

    • Can be used to some extent with runtime: shiny_prerendered, but only UI rendered through a context="server" may update in real-time.

  • Doesn't work with '3rd party' custom widgets that don't make use of bs_dependency_defer() or bs_current_theme().


library(shiny) ui <- fluidPage( theme = bs_theme(bg = "black", fg = "white"), h1("Heading 1"), h2("Heading 2"), p( "Paragraph text;", tags$a(href = "https://www.rstudio.com", "a link") ), p( actionButton("cancel", "Cancel"), actionButton("continue", "Continue", class = "btn-primary") ), tabsetPanel( tabPanel("First tab", "The contents of the first tab" ), tabPanel("Second tab", "The contents of the second tab" ) ) ) if (interactive()) { run_with_themer(shinyApp(ui, function(input, output) {})) }