Using the Chilkat ActiveX in Visual Basic 6

add a reference once, then use Chilkat classes like any other VB6 object

Windows · Visual Basic 6.0 (always 32-bit) · Chilkat ActiveX v11

The Chilkat ActiveX is a COM library: your VB6 code creates Chilkat objects such as ChilkatHttp, ChilkatJsonObject, or ChilkatCrypt2 and calls their methods. That gives a VB6 program HTTP/REST, email, FTP/SFTP, Zip, PDF, encryption, digital signatures, JSON, XML, and the rest of the Chilkat API. Chilkat objects have no user interface; you create them in code rather than placing them on a form.

On this page: Install Add the reference First program JSON into a list Events & async VB6 tips Deploying Troubleshooting

Setup

Examples

Your first program: unlock Chilkat and fetch a URL

Chilkat must be unlocked once per process with UnlockBundle. During the 30-day trial any string works; after purchase, use your license code. Put this helper in a standard module (Project » Add Module) so every form can call it:

' Module1.bas -- unlocks Chilkat once per process. Returns True when Chilkat is ready.
Public Function ChilkatReady() As Boolean
    Static unlocked As Boolean
    If Not unlocked Then
        Dim glob As New ChilkatGlobal
        unlocked = (glob.UnlockBundle("Anything for 30-day trial") = 1)
        If Not unlocked Then MsgBox glob.LastErrorText
    End If
    ChilkatReady = unlocked
End Function

Then add a command button to a form and paste this into the form's code:

Private Sub Command1_Click()
    If Not ChilkatReady() Then Exit Sub

    Dim http As New ChilkatHttp
    Dim s As String
    s = http.QuickGetStr("https://www.chilkatsoft.com/helloworld.txt")
    If http.LastMethodSuccess <> 1 Then
        MsgBox http.LastErrorText
        Exit Sub
    End If

    MsgBox s
End Sub

Press F5 and click the button. A message box shows Hello World!.

Load JSON from a web request into a ListBox

This handler downloads a small JSON document, parses it with ChilkatJsonObject, and adds each member to a ListBox named List1. The same pattern works for any REST API: send the request with ChilkatHttp or ChilkatRest, then read the fields with StringOf, IntOf, and SizeOfArray.

Private Sub Command2_Click()
    If Not ChilkatReady() Then Exit Sub

    ' {"apple":"red", "lime":"green", "banana":"yellow", ...}
    Dim http As New ChilkatHttp
    Dim jsonText As String
    jsonText = http.QuickGetStr("https://www.chilkatsoft.com/exampledata/sample.json")
    If http.LastMethodSuccess <> 1 Then
        MsgBox http.LastErrorText
        Exit Sub
    End If

    Dim json As New ChilkatJsonObject
    If json.Load(jsonText) <> 1 Then
        MsgBox json.LastErrorText
        Exit Sub
    End If

    List1.Clear
    Dim i As Long
    For i = 0 To json.Size - 1
        List1.AddItem json.NameAt(i) & vbTab & json.StringAt(i)
    Next i
End Sub

Progress events and asynchronous methods

Chilkat classes that do long operations raise events such as PercentDone, AbortCheck, and ProgressInfo. To receive them, declare the object WithEvents at the module level of a form or class module (not inside a procedure):

Private WithEvents m_http As ChilkatHttp

Private Sub Form_Load()
    Set m_http = New ChilkatHttp
End Sub

Private Sub m_http_PercentDone(ByVal percent As Long, abort As Long)
    Label1.Caption = percent & "%"
    DoEvents
    ' Set abort = 1 to cancel the operation.
End Sub

Events are raised on the same thread as the call, while the method is still running. Keep handlers short. For background work, Chilkat's ...Async methods return a ChilkatTask that runs on its own thread; read VB6 Event Callbacks before using them, because VB6 objects must not be called from a background thread. A program that uses any Async method must call FinalizeThreadPool before it exits, or the VB6 IDE can crash on exit.

Things to know when calling Chilkat from VB6

Topic	What to do
Errors	Chilkat doesn't raise VB6 errors for ordinary failures. Check the return value (or LastMethodSuccess for methods that return a string or object) and read LastErrorText, which explains exactly what went wrong. While debugging, Debug.Print obj.LastErrorText writes it to the Immediate window.
Unlocking	Call UnlockBundle once per process, for example in Sub Main or the startup form's Form_Load. Calling it again is harmless.
As New	Dim x As New ChilkatHttp creates the object the first time it's used, and re-creates it if you set it to Nothing and use it again. If you prefer explicit creation, write Dim x As ChilkatHttp and then Set x = New ChilkatHttp.
Object lifetime	Objects are released when the variable goes out of scope. Use Set obj = Nothing to release one earlier, for example a connection you are finished with.
Unicode text	VB6 strings hold Unicode, and Chilkat receives and returns Unicode strings. The standard VB6 controls, however, display text in the system's ANSI code page, so characters outside it can appear as ? in a TextBox even though the string itself is correct. Write the text to a file with Chilkat (for example ChilkatStringBuilder.WriteFile with "utf-8") to check it.
Binary data	Methods that return bytes return a Variant containing a byte array. Assign it to a Variant or a Byte() array. For large data, ChilkatBinData keeps the bytes inside Chilkat and avoids copying.
Long operations	The form doesn't repaint while a Chilkat call runs. Set timeouts such as ConnectTimeout and ReadTimeout where a class has them, and use events or async tasks for long transfers.
Chilkat v9.5 code	v11 ProgIDs are Chilkat.Http, Chilkat.Global, and so on. Older v9.5 code uses Chilkat_9_5_0.Http and a Chilkat ActiveX v9.5.0 reference. Both versions can be installed side by side; see Chilkat ActiveX v11 and v9.5 on the same computer.

Deploying a VB6 program

Your EXE doesn't contain Chilkat; it finds the Chilkat ActiveX through the Windows registry. On each computer where the program runs:

• Install and register the 32-bit Chilkat ActiveX. The simplest way is to run Chilkat's 32-bit per-machine MSI from your setup, or to have your installer copy the DLL and register it (most installer tools can register COM DLLs).
• If you register the DLL yourself on 64-bit Windows, use the 32-bit regsvr32: C:\Windows\SysWOW64\regsvr32.exe. The ActiveX DLL Registration Tutorial explains the 32-bit and 64-bit registries.
• Install the DLL to a local folder and don't move it after registering, because the registry records its path.

Troubleshooting

Message	Cause and fix
Run-time error '429': ActiveX component can't create object	The 32-bit Chilkat ActiveX isn't registered on this computer, or it is registered per-user and the program runs elevated or as another user. Install the 32-bit per-machine MSI. With late binding, also check the ProgID spelling (Chilkat.Http).
Compile error: User-defined type not defined	The Chilkat reference isn't checked. Check Chilkat ActiveX in Project » References.
MISSING: Chilkat ActiveX… in the References dialog	The project was saved on a computer with a different Chilkat installation. Uncheck the missing entry and check the current Chilkat ActiveX.
Compile error: Invalid use of New keyword	Chilkat was added under Project » Components as well as References. See VB6 Invalid Use of New Keyword.
Run-time error '438': Object doesn't support this property or method	The method or property name is misspelled, or the installed Chilkat version is older than the one the code was written for. Check the name in the reference documentation.
The IDE crashes when you close it	The program used an Async method without calling FinalizeThreadPool before exiting.
A Chilkat method returns 0 or an empty string	The operation itself failed (a network error, a bad password, an invalid file path, and so on). Show LastErrorText; it names the cause.

Next Steps

• 📖 Chilkat ActiveX Reference Documentation — every class, method, and property
• 💻 Chilkat VB6 examples — thousands of ready-to-run examples
• 📦 Chilkat ActiveX downloads (MSI installers and ZIP files)
• ✉ Contact Chilkat support

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