Parses the taxonomy of GOV.UK into a browseable tree structure.


Add this line to your application's Gemfile:

gem 'govuk_taxonomy_helpers'

And then execute:

$ bundle

Or install it yourself as:

$ gem install govuk_taxonomy_helpers


The API is provisional and is likely to change for versions < 1.0.0.

To access the taxonomy, first get the content_id of the piece of content you want the taxonomy for, then parse it to get a LinkedContentItem object.

require 'govuk_taxonomy_helpers'

taxonomy = GovukTaxonomyHelpers::LinkedContentItem.from_content_id(
  content_id: "c75c541-403f-4cb1-9b34-4ddde816a80d",
  publishing_api: Services.publishing_api

A LinkedContentItem built from a taxon can access all narrower term taxons below it and all broader term taxons above it.

A taxon may have many child taxons, but can only have one or zero parents.

# => [LinkedContentItem(title: child-1-id, ...), LinkedContentItem(title: child-2, ...)]

# => LinkedContentItem(title: root, ...)

# => [LinkedContentItem(title: root, ...), LinkedContentItem(title: taxon, ...)]

A LinkedContentItem built from an content_item that isn't a taxon can access all taxons associated with it.

# => [LinkedContentItem(title: taxon, ...),
#     LinkedContentItem(title: another-taxon, ...)]

# => [LinkedContentItem(title: root, ...),
#     LinkedContentItem(title: taxon-parent, ...),
#     LinkedContentItem(title: taxon, ...),
#     LinkedContentItem(title: another-taxon, ...)]


  • Taxonomy: The hierarchy of topics used to classify content by subject on GOV.UK. Not all content is tagged to the taxonomy. We are rolling out the taxonomy and navigation theme-by-theme.
  • Taxon: Any topic within the taxonomy.
  • Content Item: A distinct version of a document. A taxon is also a type of content item.


To run a Yard server locally to preview documentation, run:

$ bundle exec yard server --reload


  1. Fork it ( )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request


MIT License