PowerShell Script to Check Installed Software List

Use Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Select-Object DisplayName, DisplayVersion to list installed software with names and versions in PowerShell.

Examples

InputRun script on a system with Microsoft Office and Chrome installed

OutputDisplayName: Microsoft Office 365 DisplayVersion: 16.0.12325.20344 DisplayName: Google Chrome DisplayVersion: 114.0.5735.199

InputRun script on a system with no software installed in the uninstall registry key

Output

InputRun script on a system with some software missing DisplayVersion

OutputDisplayName: Example App DisplayVersion: DisplayName: Another App DisplayVersion: 2.1.0

How to Think About It

To check installed software, look into the Windows registry where installed programs are listed under a specific path. Use PowerShell to read these registry keys and extract software names and versions. This gives a simple list of installed applications.

Algorithm

1

Access the registry path for installed software.

2

Get all subkeys representing installed programs.

3

Extract the DisplayName and DisplayVersion properties from each.

4

Filter out entries without a DisplayName.

5

Output the list of software names and versions.

Code

powershell

Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* |
Where-Object { $_.DisplayName } |
Select-Object DisplayName, DisplayVersion | Format-Table -AutoSize

Output

DisplayName               DisplayVersion
-----------               --------------
Microsoft Office 365      16.0.12325.20344
Google Chrome             114.0.5735.199

Dry Run

Let's trace the script on a system with two installed programs: Microsoft Office and Google Chrome.

1

Read registry keys

Retrieve all subkeys under HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*

2

Filter entries

Keep only entries where DisplayName exists (e.g., Microsoft Office, Google Chrome)

3

Select properties

Extract DisplayName and DisplayVersion for each entry

DisplayName	DisplayVersion
Microsoft Office 365	16.0.12325.20344
Google Chrome	114.0.5735.199

Why This Works

Step 1: Access registry uninstall keys

The registry path HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall contains keys for installed software.

Step 2: Filter valid software entries

Some keys may not have a DisplayName, so we filter to only show entries with a name.

Step 3: Select and display software info

We select DisplayName and DisplayVersion to show the software name and its version clearly.

Alternative Approaches

Using Get-CimInstance

powershell

Get-CimInstance -ClassName Win32_Product | Select-Object Name, Version | Format-Table -AutoSize

This queries installed software via WMI but is slower and can trigger software repair actions.

Checking 32-bit registry path

powershell

Get-ItemProperty HKLM:\Software\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\* | Where-Object { $_.DisplayName } | Select-Object DisplayName, DisplayVersion | Format-Table -AutoSize

This lists 32-bit applications on 64-bit Windows systems.

Complexity: O(n) time, O(n) space

Time Complexity

The script reads all uninstall registry keys once, so time grows linearly with the number of installed programs.

Space Complexity

It stores the list of software entries in memory, proportional to the number of installed programs.

Which Approach is Fastest?

Reading registry keys directly is faster than querying WMI with Get-CimInstance, which is slower and can have side effects.

Approach	Time	Space	Best For
Registry Query	O(n)	O(n)	Fast listing of installed software
Get-CimInstance WMI	O(n^2)	O(n)	Detailed info but slower and may trigger repairs
WOW6432Node Registry	O(n)	O(n)	Listing 32-bit apps on 64-bit Windows