A CWK file is a document created by Apple's AppleWorks or ClarisWorks productivity suite. It may store a word processing document, spreadsheet, or presentation. CWK files were replaced by .PAGES, .KEY, and .NUMBERS files created with iWork applications.

Apple acquired ClarisWorks in 1998 and renamed it to AppleWorks. Both productivity suites were available in Mac and Windows versions. However, AppleWorks has been discontinued and was last updated in 2004. Support for CWK files has diminished since AppleWorks was discontinued. However, there is limited support still available for specific versions of CWK files. CWK word processing documents created by AppleWorks 6 may be opened by versions 1 through 4 of Pages. CWK presentation documents created by AppleWorks 6 may be opened by version 5 and earlier of Keynote. CWK spreadsheet documents created by AppleWorks 6 may be opened by version 1 and 2 of Numbers.