Download the Invoice DevKit
The Invoice Devkit is a set of files to help web developers create their own invoice themes. They allow invoice theme changes to be previewed locally before applying them to the invoices in your FreeAgent account.
Please note that you’ll only have access to a custom CSS theme if you created one before 9th June 2025.
Documentation for the devkit can be read on the Invoice Devkit GitHub repository.
Please refer to our guide to creating a custom invoice theme for in-depth help.