Doom Builder 2

Doom Builder 2 is a Doom level editor with full support for Doom, Doom II, Heretic, Hexen, Strife and all the popular source ports. Popular features include lots of customizability, prefabs, advanced drawing code, and a 3D mode which lets you browse and edit your textures, and align them, in real-time. A script editor is also included for engines that support scripting. This product is developed by Pascal "CodeImp" vd Heiden and is free software, licensed under the terms of the GNU General Public License. The project was first released in May 2009.

Doom Builder 2 is a complete rewrite of Doom Builder, with no code in common.

Forks
Two forks of Doom Builder 2 exist:
 * Doom Builder 64, created by Samuel Villarreal (Kaiser), supports mapping for the Doom64 EX engine but dropped compatibility with the other map formats.
 * GZDoom Builder, created by MaxED, is an extension of DB2 with support for many advanced ZDoom and GZDoom features, such as 3D floors, slopes, models, voxels, TEXTURES definitions, etc. It can still be used for non-ZDoom editing as well, with the appropriate configuration files, so it can be used as a complete replacement of the normal DB2.