For developers running self-hosted instances who need specific business logic not intended for public release, the "local addon" approach is standard.
This is where Zammad addon development becomes complex. The frontend is built primarily on (in newer versions) and jQuery/SCSS (in legacy parts). zammad addons
In Zammad, the terminology can be a bit tricky. While many users search for "addons" or "plugins," the platform officially categorizes these extensions under the Packages management area. What are Zammad Add-ons? zammad addons