You can avoid the fresh local install by pulling the theme files directly from the fusionauth-theme-history repository:

github.com/FusionAuth/fusionauth-theme-history/tree/main

To use this with the theme-helper repo:

Download your current customized theme using download.sh from the theme-helper repo Grab the new target version's theme files from fusionauth-theme-history Run diff-themes.sh from theme-helper against the two folders to see what changed

This approach lets you diff your customized theme against the base theme for any FusionAuth version without needing to spin up a local FusionAuth instance.

Alternative approaches:

If you prefer working directly with git, you can clone the theme-history repo and use git's built-in diffing. For example, to generate a patch between two versions:

git format-patch 1.61.0..1.64.1 --stdout > update-themes.patch

Then apply it to your theme repository:

git am --3way update-themes.patch

You can also use GitHub's built-in diff viewer to compare themes across versions directly in your browser.

Related Documentation Upgrade an Advanced Theme - Complete guide for upgrading custom themes Theme History Repository - Official documentation on using the fusionauth-theme-history repo (available back to version 1.23.0) Theme Helper - Documentation for the fusionauth-theme-helper tool Advanced Theme Upgrade Notes - Version-specific upgrade requirements and breaking changes Themes API - API reference for programmatically retrieving theme files