Get-TeamsAppUsageReport

<#
.SYNOPSIS
    Summarizes Teams app installation counts across all teams.

.DESCRIPTION
    Enumerates installed apps for every team in the tenant and produces a
    count of how many teams each app is installed in, so a security or
    licensing review is based on actual usage instead of the full app
    catalog.

.EXAMPLE
    .\Get-TeamsAppUsageReport.ps1

.NOTES
    Requires Microsoft.Graph.Teams with an active Connect-MgGraph session
    and TeamsAppInstallation.Read.All scope.

.AUTHOR
    Shehryar Hassan
#>

$teams = Get-MgTeam -All
$appCounts = @{}

foreach ($team in $teams) {
    $apps = Get-MgTeamInstalledApp -TeamId $team.Id -ExpandProperty TeamsAppDefinition
    foreach ($app in $apps) {
        $name = $app.TeamsAppDefinition.DisplayName
        if ($name) {
            $appCounts[$name] = ($appCounts[$name] ?? 0) + 1
        }
    }
}

$appCounts.GetEnumerator() | Sort-Object Value -Descending |
    Select-Object @{N="App";E={$_.Key}}, @{N="TeamsInstalledIn";E={$_.Value}} |
    Format-Table -AutoSize