From Quake Wiki
Mapping tools are devoted to the various tasks of Quake level development.
These are CAD-like programs used to construct and populate a level. They include tools to create and modify brushes, apply textures, place and modify entities, and set up simple scripting. Some of these programs have their own proprietary file format for saving levels, but they can all save or export your level to a map file, which is needed by compilers in order to generate a game-ready bsp file.
General Purpose Editors
These programs are specialized to generate terrain-like geometry out of brushes, but have no general-purpose editing capabilities. They generate map files that can then be imported into the general purpose level editors.
A number of games based on id Software's technology use map files as their level source format, but these files differ in format from game to game. Map converters are used to convert map files from one format to another, so that mappers can use a level editor that does not natively support Quake. Commonly supported game formats include Quake 2, Quake III Arena, and Half-Life.
- SleepwalkR's mapconv
These are programs that can be used to convert geometry of another file type, especially files exported by modelling software, into map files.
Map Compiling Tools
Tools to use for map compiling, a process that turns a map file into a bsp file.
QBSP, Light and Vis
Skip removal tools are standalone programs that can process a bsp file and remove all surfaces textured with a skip texture, so that those surfaces are not rendered in-game. This requires a seperate tool because skip textures are not supported by any QBSP version.
- Tyrann's original skippy.exe (has some known bugs)
- metlslime's newskip
These are programs that can reverse-compile a bsp file back into a map file, with varying results.
- bsp2prt can generate a prt file from a bsp file without needing to rebuild it from scratch using QBSP.
- bspinfo can generate statistics about a bsp file