A high-level mathematical programming language developed by Kenneth Iverson, the author of APL. J is the successor to APL and runs on a variety of platforms, including DOS, Windows, OS/2, Unix and the Macintosh. The Windows version can be used as a calculating engine for Visual Basic, in which Visual Basic is used to write the file handling and user interface portions, and J is used to program the math.

(J sharp) A programming language from Microsoft based on Java that includes most of the features of Visual J++. J# compiles into the Microsoft Intermediate Language (MSIL) for the .NET platform. J# supports COM objects and the J/Direct interface to Windows. The "sharp" in the name is the music notation symbol, which uses the pound sign. See .NET and F#.

See Visual J++.