# Installing and managing add-ons

Buy, install, update, switch on and configure add-ons from **Settings → Modules**.

Add-ons are optional modules such as Payroll, Tasks or Geofence Attendance. They are installed into the `Modules/` folder of your installation and are never overwritten by Core updates. The page is available to the super administrator of the main organization. Activate the installation first (see [Licences and activation](https://czappstudio.com/docs/installation/activation)).

## What each card shows

| Card shows | Meaning | What you can do |
|---|---|---|
| **In the store** + **Buy now** | Not owned and not installed | Open its page on czappstudio.com and buy it |
| **Free** + **Claim free** | A free add-on you have not claimed yet | Open its page on czappstudio.com and complete the order; there is nothing to pay |
| **Owned** + **Install 1.2.0** | Owned, not yet on this server | Install it |
| **Enabled** / **Disabled** | Installed and licensed | Switch it on or off |
| **Update to 1.3.0** | A newer release you are entitled to | Update it |
| **Not licensed** / **Off until licensed** | Files are on the server but no licence is attached | Buy it, or attach your licence in your account |
| **Configure** | The add-on has settings | Open its settings without leaving the page |

Use **Filters → Available to install** to see only add-ons that are not on the server yet.

![Settings → Modules: Filters (1), Buy now (2) on an add-on in the store, and Configure (3) on an installed one.](https://media.czappstudio.com/screens/docs/modules-store/light-f75dea0e58-2880.webp)

## Buy an add-on

Choose **Buy now**. The add-on's page opens on czappstudio.com in a new tab; complete the purchase there. A purchase started from **Buy now** is attached to this installation's licence automatically. Back in the product, choose **Check for updates**; the card shows **Install**.

Free add-ons show **Claim free** instead. The steps are the same, except that the order completes without payment; you need to be signed in to your czappstudio.com account. A free add-on receives updates for as long as the Core licence it is attached to.

## Install or update

Choose **Install** (or **Update to …**), then **Install**. Keep the window open while it:

1. downloads the release, checks it against CZ App Studio's signature, and places the files in `Modules/<Name>`;
2. switches the add-on on, which runs its database changes and adds its permissions.

When it finishes, choose **Configure** if the add-on has settings. Some add-ons need another first: Calls needs Chat, and the Microsoft 365 add-ons need the Microsoft 365 Connector. Install and enable those first.

## If an install fails

The dialog shows what to fix on the server, then **Try again**. The previous copy of an add-on is kept until the new one is in place.

| Message | Fix |
|---|---|
| *PHP (running as www-data) cannot write to …/Modules* | Give the PHP user write access, for example `sudo chown -R www-data /path/to/backend/Modules`, then retry. |
| *Not enough free disk space* | Free space on the server's storage disk. |
| *The PHP zip extension is missing* | Install and enable it (for example `php-zip`) and restart PHP. |
| *The download does not match the store's signature* | Nothing was installed. Try again; if it repeats, contact support. |
| *The database refused a change* | The add-on stays off. Check the database user's permissions (CREATE, ALTER, INDEX) and retry. |
| *This add-on needs a licence* | Buy it, or attach it to this installation's licence in your account. |

## Switch off or remove

**Disable module** hides the add-on and its menus; its data is kept and comes back when you switch it on again. An add-on cannot be switched off while another add-on or an attendance policy uses it.

## Free modules and your own modules

Modules you build yourself have no store code and are never licensed or updated by CZ App Studio. See [Building your own module](https://czappstudio.com/docs/installation/custom-modules).