Find how many SQL Server instances are installed
Here are some options using what is already available on a server with Windows Server and SQL Server installed.

You can list Services on a server with a name starting with SQL Server (...:

sc \\IP_or_Name query | find /I "SQL Server ("


IP_or_Name is the IP or DNS name of the Windows Server 20xx server.

Or with Powershell:

Get-Service | Where-Object {$_.DisplayName -like "SQL Server (*"}




You can look at the content of the registry key HKLM:\Software\Microsoft\Microsoft SQL Server\Instance Names\SQL using Regedit. 

You can also use Powershell:

Get-ItemProperty 'HKLM:\Software\Microsoft\Microsoft SQL Server\Instance Names\SQL'


Key HKLM:\Software\Microsoft\Microsoft SQL Server\InstalledInstances gives a list of name separated by line breaks.



Powershell commands can be executed remotely using Invoke-Command:

Invoke-Command -ComputerName computer -ScriptBlock { command } -Credential username




Using sqlcmd you can get a list of the instances which broadcast their names on the network:

sqlcmd -L


Or with Powershell which has the advantage of showing Version number:

[System.Data.Sql.SqlDataSourceEnumerator]::Instance.GetDataSources()