The file extension CWK is associated with the AppleWorks Productivity Suite or ClarisWorks which are both Macintosh programs. Both AppleWorks and ClarisWorks are older Apple programs which have been discontinued; however, if the files were created with any of these programs, it is still possible to access the content in them.
CWK files can contain spreadsheets, presentations, drawings, or a simple word processing document. Apple replaced AppleWorks with iWork which can open older ClarisWorks and Apple Works files and save them in a newer format.
CWK files can also be associated with CattleMac data file program which is a record keeping and management system for farming operations. Or the file can be related to GCPrevue which is an industry standard program for describing printed circuit boards. In this case files contain languages for using vector photo plotters. CWK files related to these programs are not as common as those associated with AppleWorks.
How to Open CWK Files
Obviously if you have a CWK file that was created using ClarisWorks or AppleWorks, you will be able to open and edit CWK files. This applies to both Mac and Windows-based PCs with the appropriate AppleWorks program installed.
To try and identify the contents of the file, sometimes you can open CWK files using any basic text editor such as Notepad or TextEdit. If the content includes a document as opposed to a drawing, you may have success with reading the file. Then you can copy and paste the content into another application where you can easily open and edit it. It is also important to mention that Microsoft Word is not capable of opening and reading CWK files.
You can also open and view CWK files using a third party conversion program. There are a number of these programs available for opening CWK files. A few of the programs you can try are Conversions Plus or DocxConverter which is available on the CNET website or you can try performing an online search to locate additional third party CWK file conversion programs.
There is also a program called MacText which is a conversion application known for being able to open CWK files. It has a simple and straightforward user interface and allows you to input your file name, choose the source format, and then select the target format. You can download the demo copy from the MacText website to use for a limited time before you are required to pay for the full version of the program.