There is a list of Freemarker editor plugins here, which may be helpful: https://freemarker.apache.org/editors.html Some editors not listed there have their own extensions for Freemarker, such as Visual Studio Code. Sublime may have one as well, but I haven't used that editor recently. TextMate and VS Code are my go to choices for most editing

Thanks - I should be able to install VS Code without prior authorisation from our IT team