This article is from the Apple II Programming FAQ, by Jeff Hurlburt with numerous contributions by others.
Quite a few. Apple Integer BASIC (in-ROM on the first Apple II's), can be loaded into II+ and later models. Applesoft, a floating point BASIC, is in-ROM on all models starting with the II+. Older Apple II's can load-in Applesoft or, via a plug-in board, access it from ROM. Then, there is MD BASIC, the BASIC-like MacroSoft from MicroSparc, a beta version of Apple's GS BASIC, and the new (1998) Byte Works GS BASIC! Users who want to speed up their AppleSoft programs can use a BASIC compiler such as TASC or Einstein. Other Apple II languages are Apple Fortran, UCSD Pascal, Orca (ByteWorks) Pascal, Kyan Pascal, Terrapin Logo, Apple Logo, two Logos from ByteWorks, Isys Forth, Master Forth, (and many other Forths), Modula2, Aztec C, Orca/C, ... . Hyperstudio and HyperCard let you create stacks. You can find a comprehensive listing in Larry Virden's "Apple II Programmer's Catalog of Languages and Toolkits" at http://www.purl.org/net/lvirden/Misc/apple2-languages.txt . To the above you can add several assemblers including Merlin, Orca/M, an assembler from Ninja Force, and the MicroSparc Assembler. For Orca manuals and to order the Orca languages see Byte Works products at Syndicomm ( http://www.syndicomm.com/products/ ). --Rubywand, Jeffrey Iverson, Andrew Roughan, Willi Kusche