Installing an add-on

You can install an add-on in two ways:

Upload & install in the admin panel. This is the recommended way.
Manual install over FTP/SFTP/SSH. Use it if the upload fails, for example because of upload size limits or file permissions.

Both methods give the same result.

Option A: Upload & install (recommended)

Log in to the admin panel as a root administrator.
Go to Add-ons → Manage add-ons.
Click the + button in the top right (Upload & install add-on).
Choose the kv_<addon>-<version>.zip archive exactly as you downloaded it. Don’t unpack it and re-zip it.
Click Upload & install.
CS-Cart unpacks the archive, copies the files, creates any database tables and installs the language variables. When it finishes, the add-on appears in the list.
Make sure the status is Active. If it isn’t, open the status menu next to the add-on and choose Active.
Click the add-on name to open its settings.

During installation, CS-Cart copies the storefront templates from var/themes_repository/ into every installed theme under design/themes/. That is why the add-on works with your current theme right away.

If the upload fails

Symptom	Likely cause and fix
“File is too large” or a blank page	PHP’s `upload_max_filesize` / `post_max_size` is lower than the archive size. Raise the limits or use Option B.
“Permission denied” or “Unable to write”	The web server user can’t write to `app/addons`, `design`, `js` or `var`. See Permissions.
“The add-on already exists”	The add-on is already on the server, possibly left over from an earlier install. Uninstall it, or follow Updating add-ons.
Compatibility error	Your CS-Cart version or edition isn’t supported. See the compatibility policy.

Option B: Manual installation (FTP / SSH)

Unpack the archive on your computer. Inside you will find folders that mirror the CS-Cart root, for example:

app/addons/kv_<addon>/
design/backend/templates/addons/kv_<addon>/
var/themes_repository/responsive/templates/addons/kv_<addon>/
var/langs/en/addons/kv_<addon>.po
js/addons/kv_<addon>/

Upload these folders to your CS-Cart root directory (the one that contains admin.php and config.local.php) and merge them with the existing folders. Don’t replace whole directories. Only new files are added.
In the admin panel, go to Add-ons → Manage add-ons. The add-on shows up as Not installed. Use the browse filter to show all add-ons if you can’t see it.
Click Install next to the add-on.
Set the status to Active if needed, then open its settings.

Over SSH:

cd /path/to/cscart
unzip ~/kv_<addon>-<version>.zip -d /tmp/kv_addon
cp -R /tmp/kv_addon/* .

Then click Install in the admin panel as described above.

File permissions

The web server (PHP) user has to be able to read every add-on file and write to CS-Cart’s cache directories. A typical secure setup:

# owner = the user PHP runs as (e.g. www-data, nginx, or your hosting account)
find app/addons/kv_<addon> design js var/themes_repository -type d -exec chmod 755 {} \;
find app/addons/kv_<addon> design js var/themes_repository -type f -exec chmod 644 {} \;
chmod -R u+rwX var images      # cache, compiled templates, uploaded files

If PHP runs as a different user than the file owner, you may need 775/664 on design, var and images. Ask your host if you’re unsure. Never leave config.local.php writable after installation.

Clear the cache

After installing, clear the cache so the new templates, styles and scripts load:

Admin panel: in the top-right gear menu, click Clear cache. You can also go to Administration → Storage → Clear cache.
URL shortcut: open https://your-store.com/admin.php?cc&ctpl. Use your renamed admin script if you changed admin.php. cc clears the data cache and ctpl clears compiled templates.
Server: delete the contents of var/cache/. This works only with the default file cache backend.

Then reload the storefront. Some add-ons also need a block placed in Design → Layouts. The add-on’s Usage page tells you if that’s the case.

Multi-Vendor

Only the marketplace owner (root admin) can install add-ons. Vendors never see the Add-ons menu. Some add-ons add vendor panel pages or settings, which appear automatically after installation. See Multi-Vendor notes.

Uninstalling

Go to Add-ons → Manage add-ons, open the add-on’s menu and choose Uninstall. Our add-ons remove their own database tables, settings and language variables on uninstall, so back up first if you might want that data again. Disabling the add-on (status Disabled) keeps all data and simply turns the feature off.