Using backwards compatibility

Version 7 of the Prototype Kit uses the new GOV.UK Design System. It is not compatible with prototypes built with older versions by default.

Backwards compatibility lets you import a large old prototype into version 7, without having to rewrite it. You can update old pages one by one as you need to, and add new pages.

You will end up with 2 'apps' in your prototype:

/app using version 7

/app/v6 using version 6

If any pages or routes exist in both apps, the one in version 7 will win.


  1. Make a note of your Prototype Kit version in VERSION.txt in your prototype folder.

  2. Make sure you have a backup of your prototype folder, for example by copying it to another folder or by uploading to GitHub.

  3. Delete everything in your prototype folder except for the app and .git folders. (.git may be hidden).

  4. Rename your app folder to v6

  5. Find and replace all instances of /public/ to /public/v6/ in your code. In Atom, press cmd shift F. It looks like this: Screenshot of Atom find and replace

  6. Download the latest Prototype Kit and unzip it.

  7. Copy everything from the new Prototype Kit folder into your prototype folder.

  8. Move your v6 folder into the new app folder.

  9. Update app/config.js to your settings, in particular the serviceName. You can then safely remove app/v6/config.js.

  10. On the command line, in your prototype folder, run npm install, then npm start.

  11. If your previous Prototype Kit version was older than 6.3.0, follow the guidance below about updating from older versions.

Updating pages to use version 7

You can now create new pages using version 7 by working in the app/views folder.

You can update old pages by moving them from app/v6/views to app/views. You will then need to update the code on these pages to work with version 7. See the updating your code guide in the GOV.UK Design System.

Updating from versions older than 6.3.0

The instructions above are for updating from version 6.3.0 of the Prototype Kit. If you had an older version, follow the normal instructions then run the commands below:


npm install govuk-elements-sass@3.0.1 govuk_frontend_toolkit@5.1.2 govuk_template_jinja@0.22.1

6.1.0 or 6.0.0

npm install govuk-elements-sass@3.0.1 govuk_frontend_toolkit@5.1.2 govuk_template_jinja@0.19.2