[r0b3rt]

Name checker url;
- https://minecraft.net/haspaid.jsp?user=

Okay, so what you need to do is create a new windows form application in vb.net.
Add these things from the toolbox to the form;
x1 System.windows.form.textbox
x2 System.windows.form.button
x2 System.windows.form.label
x2 System.windows.forms.Listbox
x1 Open file dialog
x1 BackGround worker
Name the two labels;
Checked: & Available:
Name the two buttons;
Check! & Load names
Put the first textbox in the top left, and the two buttons on the right of it.
Put the two labels under, and the listboxes under the labels.
CODE:
-
Whole code:
Spoiler (Click to View)

Code

Public Class Form1

    Dim file As String
    Dim currentWorkerName As String
    Dim currentWorkerNameA As Boolean

    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
        TextBox1.ForeColor = Color.Black
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        If TextBox1.Text = "" Then
            MsgBox("Empty minecraft username!", MsgBoxStyle.Information, "@Available Notification")
            Return
        End If
        Dim wc As New Net.WebClient
        Dim res As String
        res = wc.DownloadString("https://minecraft.net/haspaid.jsp?user=" + TextBox1.Text)
        ListBox1.Items.Add(TextBox1.Text)
        If res.Contains("false") Then
            TextBox1.ForeColor = Color.LightGreen
            ListBox2.Items.Add(TextBox1.Text)
        Else
            TextBox1.ForeColor = Color.Red
        End If
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        ofd.Filter = "Text Files (*.txt)|*.txt"
        ofd.ShowDialog()
        If Not ofd.FileName = "" Then
            file = ofd.FileName
            bgWorker.RunWorkerAsync()
        End If
    End Sub

    Private Sub bgWorker_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles bgWorker.DoWork
        If System.IO.File.Exists(file) = False Then
            Return
        End If
        Dim objReader As New System.IO.StreamReader(file)
        Dim count As Integer = 0
        Do While objReader.Peek() <> -1
            count += 1
            currentWorkerName = objReader.ReadLine()
            Dim wc As New Net.WebClient
            Dim res As String
            res = wc.DownloadString("https://minecraft.net/haspaid.jsp?user=" + currentWorkerName)
            If res.Contains("false") Then
                currentWorkerNameA = True
            Else
                currentWorkerNameA = False
            End If
            bgWorker.ReportProgress(count)
            System.Threading.Thread.Sleep(150)
        Loop
    End Sub

    Private Sub bgWorker_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles bgWorker.ProgressChanged
        ListBox1.Items.Add(currentWorkerName)
        If currentWorkerNameA Then
            ListBox2.Items.Add(currentWorkerName)
        End If
    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub
End Class

I will update this with more informative info & pics in the morning.

[01010]

@Siyabent I figure this guy won't update it so I'll just use his code & make a tutorial here :)

[01010]

Posted a tutorial on this code if you guys are interested