CkPython vs. Chilkat2-Python

Chilkat provides two Python modules. Both are the same Chilkat library underneath — the same classes, methods, and properties, released together with the same version number — but they present that library to Python in two different styles. This page explains the difference and which one to choose.

Short answer For a new project, use Chilkat2-Python (pip install chilkat2, import chilkat2). It has a natural Python API: properties are Python properties, methods return values directly, and binary data is handled with standard Python bytes-like objects. CkPython (pip install chilkat, import chilkat) is the original module. It remains fully supported and receives every new class and method, so an existing CkPython application does not need to be converted.

Where they came from

CkPython is the original Chilkat module for Python. It was produced for many years with SWIG, which wraps the Chilkat C++ classes more or less as-is, so the API has a C++ flavor: properties are accessed through get_Xxx() and put_Xxx() methods, and a method that returns a string has two forms — one that fills a CkString argument and returns a bool, and a lower-case-initial one that returns the Python str.

Chilkat2-Python was introduced later as a fresh, hand-designed Python API for the same library. It has never used SWIG: it is generated directly from the Chilkat API definition by Chilkat's own generator.

As of Chilkat v11.6.1, CkPython no longer uses SWIG. It is now produced by the same kind of in-house generator as Chilkat2-Python. Its API was kept exactly the same, so this changed nothing for existing code, but the two modules are now built the same way and have the same platform and Python-version coverage (see the table below).

The difference in code

CkPython (`import chilkat`)

import chilkat

imap = chilkat.CkImap()
imap.put_Ssl(True)
imap.put_Port(993)
success = imap.Connect("imap.example.com")
if not success:
    print(imap.lastErrorText())

Chilkat2-Python (`import chilkat2`)

import chilkat2

imap = chilkat2.Imap()
imap.Ssl = True
imap.Port = 993
success = imap.Connect("imap.example.com")
if not success:
    print(imap.LastErrorText)

The class, method, and property names are the same in both modules, and both follow the Chilkat reference documentation. What differs is the Python spelling:

	CkPython	Chilkat2-Python
Import	`import chilkat`	`import chilkat2`
Class names	`chilkat.CkHttp`, `chilkat.CkZip`, `chilkat.CkBinData`	`chilkat2.Http`, `chilkat2.Zip`, `chilkat2.BinData`
Properties	`obj.get_Port()`, `obj.put_Port(993)`, `obj.lastErrorText()`	`obj.Port`, `obj.Port = 993`, `obj.LastErrorText`
Methods returning a string	Two forms: `ok = http.QuickGetStr(url, ckStr)` fills a `CkString`; `s = http.quickGetStr(url)` returns `str`	One form: `s = http.QuickGetStr(url)` returns `str` (an empty string on failure; check `LastMethodSuccess`)
Binary data	`bytes` in and out: `bd.AppendData(b, len(b))`, `bd.GetData()` returns `bytes`; older code also uses `CkByteData`. See Passing binary data between Chilkat and CkPython.	Any bytes-like object in (`bytes`, `bytearray`, `memoryview`); a read-only `memoryview` out — `bytes(bd.GetBinary())` to copy it. See Passing binary data between Chilkat and Python and Explaining the Python memoryview.
Method failures	Neither module raises Python exceptions for a Chilkat method that fails; the method returns `False` / an empty result and `LastErrorText` explains why. Exceptions are raised only for Python-level misuse (wrong argument type or count).
Asynchronous calls	`task = http.QuickGetStrAsync(url)`, `chilkat.CkTask`	`task = http.QuickGetStrAsync(url)`, `chilkat2.Task`
Progress-event callbacks	Yes — subclass e.g. `chilkat.CkHttpProgress` and pass it to `put_EventCallbackObject()`; the progress, abort-check, and task-completed events are delivered to your Python methods.	Not available. Use the `Async` methods and poll the `Task` (`PercentDone`, `Finished`, `Cancel()`) instead.
Examples	example-code.com/python	example-code.com/chilkat2-python

Requirements, downloads, and installation

Since v11.6.1 (September 2026) the two modules have identical requirements. Both target the CPython stable ABI, so there is one binary per operating system and processor that works with every Python from 3.7 onward — including Python versions released after the module was built. Python 3.6 and earlier (and Python 2) are no longer supported by either module; the last per-version builds remain available on the Chilkat2 Python older versions page.

	CkPython	Chilkat2-Python
Python versions	CPython 3.7 and later (one build for all of them)
Platforms	Windows x64, win32, and ARM64 · Linux x86_64, arm64, and armv7l · Alpine Linux x86_64 and arm64 · macOS Apple silicon and Intel
pip	`pip install chilkat`	`pip install chilkat2`
What the download contains	`chilkat.py` plus the extension `_chilkat.so` (`_chilkat.pyd` on Windows); both go in site-packages	Just the extension `chilkat2.so` (`chilkat2.pyd` on Windows)
Download pages	Chilkat Module for Python (CkPython)	Chilkat2 Module for Python

Can both be installed at the same time?

Yes. The modules have different names (chilkat and chilkat2) and different files, so they coexist in the same site-packages directory and can even be imported into the same program. Objects cannot be passed between them, however: a chilkat.CkCert is not a chilkat2.Cert.

Moving from CkPython to Chilkat2-Python

There is no automatic converter, but the changes are mechanical: drop the Ck prefix from class names, turn get_X()/put_X(v) into obj.X/obj.X = v, replace the lower-case-initial string methods (quickGetStr, lastErrorText, …) with the capitalized names that now return the value directly, and replace CkString/CkByteData out-arguments with the returned str or memoryview. Every example on example-code.com exists in both flavors, which makes a side-by-side comparison easy.