xApp style guide

When building xApps, it makes a lot of sense to stick to the design (colour palette, font, etc.) as used by XUMM to offer the best user experience to xApp users.

Font family

The main application uses the font-family: proxima-nova, sans-serif. Only when using this font for your (web) xApp to be embedded in XUMM, use this stylesheet:

<link rel="stylesheet" href="//use.typekit.net/vtt7ckl.css">

When offering your application anywhere else than as embedded (web) xApp, check your licensing needs and requirements for the use of Proxima Nova.


Starting XUMM version 1.1 four colour palettes are available. The colour the app is running in will be passed to the xApp in the style parameter, see the xapp/ott/:token documentation (applies to the SDK as well).

Used colour palette codes:

  • DARK


Your xApp launch URL will receive a GET parameter (query param) named xAppStyle containing the colour palette name as active on the client device. If your xApp URL is eg.:


... the URL opened will be:


Standard CSS stylesheets

The four available themes are shipped as Bootstrap (version 4.5) rolled stylesheets, ready to use. You can include a Bootstrap 4.5 stylesheet by pointing to:


The {theme} element should be replaced by the theme name in lower case notation.

SPA / Front-end app only

To load the right stylesheet dynamically in an environment without a backend, consider using this script in your <head>:

  var theme = ((new URLSearchParams(document.location.href))
               .get('xAppStyle') || 'light').toLowerCase()
  var link = document.createElement('link')
  link.href = 'https://xumm.app/assets/themes/xapp/xumm-'
    + theme + '/bootstrap.min.css'
  link.type = 'text/css'
  link.rel = 'stylesheet'