Installation & first sync

System requirements

Installation

CYNC is distributed as a single Cync.Setup.exe installer. It handles .NET runtime installation, Windows Service registration, and firewall rules. All prerequisites are bundled for offline installation.

Interactive install

Double-click Cync.Setup.exe to launch the installer wizard. Accept the EULA, choose the installation directory, and select which features to install:

• CYNC Service - the sync engine (always installed)
• CYNC Admin Dashboard - the WinUI 3 desktop UI (optional on Server Core)

Silent install

For automated deployment via SCCM, Intune, or Group Policy:

The installer registers CYNC as a Windows Service set to start automatically. After installation, the service starts on the next reboot or when manually started.

For a complete list of all parameters (InstallService, InstallUI, EnableRemoteAdmin, InstallFolder), install modes (/quiet, /passive), and enterprise deployment examples, see the Installation Reference.

Upgrade

CYNC uses the WiX major-upgrade pattern. Installing a newer version automatically uninstalls the previous version, preserving configuration and the local SQLite database. No manual uninstall is required.

First launch

After installation, launch the CYNC admin dashboard from the Start menu. On first launch, the dashboard connects to the local CYNC service via a named pipe.

The dashboard is a native WinUI 3 application that follows the Windows 11 design language (Mica material, Segoe Fluent Icons, system light/dark theme). It provides:

• Dashboard - status summary, sync trigger, real-time progress during sync
• Configuration - Entra ID tenant settings (Tenant ID, Client ID, certificate), sync settings (interval, contact folder name, profile photos), field mappings, and exclusion filters
• Sources - select Entra ID groups to sync from, or sync all users
• Target Users - manage which Exchange Online mailboxes receive contacts
• Sync History - paginated log of every sync run with timestamps, counts, and errors
• License - activate, deactivate, or view your current license
• Logs - real-time log viewer with level filtering (All, Information, Warning, Error)
• About - version information, update checker with one-click install, and credits

Connect to Entra ID

Before CYNC can sync contacts, you need to create an App Registration in Microsoft Entra ID and provide the credentials in the CYNC dashboard. CYNC uses certificate-based authentication - no client secrets or stored passwords.

In the dashboard, navigate to the Configuration page and:

1. Enter your Tenant ID - your Microsoft 365 tenant GUID
2. Enter your Client ID - the Application (client) ID from your App Registration
3. Click Generate/Renew Certificate to create and install a certificate automatically. CYNC generates a self-signed certificate, stores the private key in the Local Machine certificate store, exports the public key (.cer), and fills in the thumbprint for you.
4. Upload the exported .cer file to your App Registration in the Entra admin center (Certificates & secrets → Upload certificate).

For detailed instructions including manual certificate generation via PowerShell and API permission setup, see the Entra ID Setup guide.

Define target users

Target users are the Exchange Online mailboxes that will receive the synced contacts. CYNC creates a dedicated contact folder in each target user's mailbox.

You can define target users in four ways:

The number of target users counts against your license limit. The number of source users synced from Entra ID is unlimited.

Run your first sync

1. Navigate to the Dashboard page.
2. Click Sync Now to trigger a manual sync.
3. Watch the real-time progress bar as CYNC fetches users from Entra ID, diffs them against existing contacts, and creates or updates contacts in each target mailbox.
4. Once complete, check the Sync History page for a summary: contacts created, updated, deleted, errors encountered, and total duration.

Automatic sync

By default, CYNC runs on a configurable interval (default: every 6 hours). You can change the interval in the Configuration page. The service continues to sync on schedule even when the dashboard is closed - it runs as a Windows Service in the background.

What gets synced

CYNC reads the following fields from Entra ID user profiles and writes them as contact properties. Each field can be individually toggled on or off in the Configuration page:

• Display name
• Given name & surname
• Email addresses
• Job title
• Department
• Company name
• Office location
• Business phone numbers
• Mobile phone
• Business address
• Profile photo (optional - toggle in Configuration)

Contact folder & exclusion filters

By default, CYNC stores contacts in a folder named CYNC inside each target mailbox. You can customize this name in the Configuration page.

To limit which Entra ID users are synced as contacts, configure exclusion filters in the Configuration page:

• Excluded departments - comma-separated list of department names to skip (e.g. IT, Contractors, Interns)
• Excluded UPN patterns - comma-separated patterns to exclude by user principal name (e.g. admin@*, svc-*)
• Exclude contacts without phone - skip Entra ID users that have no business or mobile phone number (useful for reducing noise)

License activation

After purchasing a CYNC license, you will receive an RSA-signed license key by email within minutes.

1. Open the CYNC dashboard and navigate to the License page.
2. Paste the license key string into the input field.
3. Click Activate.

The license is an RSA-2048 signed payload activated via the online activation server. Each key can only be active on one machine at a time, ensuring single-machine licensing.

Transferring a license

Licenses are bound to the machine on activation for integrity, but fully transferable. To move CYNC to a new server:

1. Open the dashboard on the old machine and click Deactivate.
2. Install CYNC on the new machine.
3. Paste the same license key and click Activate.

Free tier

CYNC includes a built-in free tier for up to 10 target users - no license key required. This lets you test the full product in your environment. For more than 10 users, purchase a license key. To upgrade, simply paste your license key on the License page and click Activate.