diff --git a/MVVM/Services/RegistryService.ps1 b/MVVM/Services/RegistryService.ps1
new file mode 100644
index 0000000..9274599
--- /dev/null
+++ b/MVVM/Services/RegistryService.ps1
@@ -0,0 +1,68 @@
+class RegistryService {
+
+    static [string] $BasePath = "HKLM:\SOFTWARE\Policies\Mozilla\Firefox"
+    static [string] $ExtPath  = "HKLM:\SOFTWARE\Policies\Mozilla\Firefox\ExtensionSettings"
+
+    static [void] EnsureKey([string]$path) {
+        if (-not (Test-Path $path)) { New-Item -Path $path -Force | Out-Null }
+    }
+
+    static [void] SetString([string]$path, [string]$name, [string]$value) {
+        [RegistryService]::EnsureKey($path)
+        Set-ItemProperty -Path $path -Name $name -Value $value -Type String
+    }
+
+    static [void] SetDWord([string]$path, [string]$name, [int]$value) {
+        [RegistryService]::EnsureKey($path)
+        Set-ItemProperty -Path $path -Name $name -Value $value -Type DWord
+    }
+
+    static [void] RemoveValue([string]$path, [string]$name) {
+        Remove-ItemProperty -Path $path -Name $name -ErrorAction SilentlyContinue
+    }
+
+    static [void] RemoveKey([string]$path) {
+        if (Test-Path $path) { Remove-Item -Path $path -Recurse -Force }
+    }
+
+    static [void] DeployAddon([AddonModel]$addon) {
+        $key = Join-Path ([RegistryService]::ExtPath) $addon.Id
+        [RegistryService]::SetString($key, "installation_mode", "force_installed")
+        if ($addon.InstallUrl) {
+            [RegistryService]::SetString($key, "install_url", $addon.InstallUrl)
+        }
+    }
+
+    static [void] BlockAddon([string]$addonId) {
+        $key = Join-Path ([RegistryService]::ExtPath) $addonId
+        [RegistryService]::SetString($key, "installation_mode", "blocked")
+    }
+
+    static [void] SetWildcard([string]$mode) {
+        $key = Join-Path ([RegistryService]::ExtPath) "*"
+        [RegistryService]::SetString($key, "installation_mode", $mode)
+    }
+
+    static [void] RemoveJsonString() {
+        [RegistryService]::RemoveValue([RegistryService]::BasePath, "ExtensionSettings")
+    }
+
+    static [hashtable] GetExtensionSettings() {
+        $result = @{}
+        if (-not (Test-Path ([RegistryService]::ExtPath))) { return $result }
+        Get-ChildItem ([RegistryService]::ExtPath) -ErrorAction SilentlyContinue | ForEach-Object {
+            $props = Get-ItemProperty $_.PSPath -ErrorAction SilentlyContinue
+            $result[$_.PSChildName] = @{
+                installation_mode = $props.installation_mode
+                install_url       = $props.install_url
+            }
+        }
+        return $result
+    }
+
+    static [string] GetValue([string]$path, [string]$name) {
+        try {
+            return (Get-ItemProperty $path -Name $name -ErrorAction Stop).$name
+        } catch { return $null }
+    }
+}