This script uses Microsoft Graph PowerShell SDK. It is helpful to identify and inventorize all the Azure AD Applications registered in your tenant. The script enumerates the KeyCredentials (Certificates) and PasswordCredentials (Client Secret) keys, expiration dates, owner and other useful information.

Get-AzureADAppCredentialsInfo.ps1

Connect-MgGraph -Scopes "User.Read.All","Group.ReadWrite.All","Application.Read.All", "Application.ReadWrite.All", "Directory.Read.All", "Directory.ReadWrite.All", "Directory.AccessAsUser.All"
$Apps = Get-MgApplication -All
$today = Get-Date
$credentials = @()

$Apps | %{
    $aadAppObjId = $_.Id
    $app = Get-MgApplication -ApplicationId $aadAppObjId 
    $owner = Get-MgApplicationOwner -ApplicationId $aadAppObjId

    $app.KeyCredentials | %{
        #write-host $_.KeyId $_.DisplayName
        $credentials += [PSCustomObject] @{
            CredentialType = "KeyCredentials";
            DisplayName = $app.DisplayName;
            AppId = $app.AppId;
            ExpiryDate = $_.EndDateTime;
            StartDate = $_.StartDateTime;
            #KeyID = $_.KeyId;
            Type = $_.Type;
            Usage = $_.Usage;
            Owners = $owner.AdditionalProperties.userPrincipalName;
            Expired = if(([DateTime]$_.EndDateTime) -lt $today) {"yes"} else{ "No"};
            }
    }


    $app.PasswordCredentials | %{
        #write-host $_.KeyId $_.DisplayName
        $credentials += [PSCustomObject] @{
            CredentialType = "PasswordCredentials";
            DisplayName = $app.DisplayName;
            AppId = $app.AppId;
            ExpiryDate = $_.EndDateTime;
            StartDate = $_.StartDateTime;
            #KeyID = $_.KeyId;
            Type = 'NA';
            Usage = 'NA';
            Owners = $owner.AdditionalProperties.userPrincipalName;
            Expired = if(([DateTime]$_.EndDateTime) -lt $today) {"yes"} else{ "No"};
        }
    }
}

$credentials | FT -AutoSize 

# Optionally export to a CSV file
#$credentials | Export-Csv -Path "AppsInventory.csv" -NoTypeInformation 

Is it possible to do this with C# or python.. like need to implement this in web application level

@ashmsport yes, see this: https://dev.to/svarukala/manage-azure-ad-enterprise-applications-permissions-using-microsoft-graph-powershell-222m

@amlijupnandanan yes, you must use MS Graph rest endpoint. The above script essentially doing the same except it's using PS.