GOV.UK Prototype Filters is a collection of Nunjucks template filters to manipulate and transform:


Node.js v16 or later.


npm install govuk-prototype-filters

GOV.UK Prototype Filters are designed to work with the GOV.UK Prototype Kit.

If you are using v13 or later of the kit, the components will be immediately available once you have installed the package, and can be managed alongside other plugins in your prototype.

You can also use these filters with earlier versions of the GOV.UK Prototype Kit, or within other projects.

About Nunjucks filters

Variables in Nunjucks templates can be modified using filters. Filters are separated from the variable by a pipe symbol (|) and can have optional arguments in parentheses. Multiple filters can be chained, with the output of one filter is applied to the next.

For example, {{ siteName | striptags | lower }} will remove all HTML tags from the given variable and lower-case the output. If the siteName variable referenced the text <p>GOV.UK</p>, the output would be

Filters that accept arguments have parentheses around the arguments, like a function call. For example: {{ list | join(", ") }} will join a list with commas.

striptags, title and join are examples of filters built into Nunjucks. GOV.UK Prototype Filters provides a collection of filters that can be used alongside these.


The project repository is public and anyone can contribute.

View this project on GitHub.