Editors
Bricksmith 
developed by Allen Smith allows you to create virtual instructions for your Lego creations on your Mac.
Website: bricksmith.sourceforge.net/
LDCad
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LDCad, developed by Roland Melkert, is a multiplatform LDraw editor that lets you edit LDraw model documents in real-time. LDCad is part of the AIOI - LDraw All-In-One-Installer.
Website: www.melkert.net/LDCad/
LeoCAD 
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LeoCAD, developed by Leonardo Zide, is a CAD program for creating virtual LEGO models. LeoCAD is part of the AIOI - LDraw All-In-One-Installer.
Website: www.leocad.org/
MLCad 
also known as Mike's LEGO CAD, is a LDraw CAD program developed by Michael Lachmann, which has the ability to create and manage Multi-Part Document files. You can create models with it and add steps to create instructions. MLCad is part of the AIOI - LDraw All-In-One-Installer.
Website: mlcad.lm-software.com
Viewers and Publishing
LDView 
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LDView, developed by Travis Cobbs, is a real-time 3D viewer for displaying LDraw models using hardware-accellerated 3D graphics. LDView is part of the AIOI - LDraw All-In-One-Installer.
Website: tcobbs.github.io/ldview/
LPub3D 
LPub3D, developed by Trevor Sandy, is a WYSIWYG editing application for creating LEGO style digital building instructions. Portions of LPub3D are based on LPUB© 2007-2009 Kevin Clague, LeoCAD© 2015 Leonardo Zide and additional third party components. LPub3D is part of the AIOI - LDraw All-In-One-Installer.
Website: sourceforge.net/projects/lpub3d//
LIC 
LIC - LEGO Instruction Creator, developed by Jeremy Czajkowski, is a cross-platform, Python, OpenGL & Qt powered desktop application for creating and editing LEGO instruction books. LIC imports 3D models, organizes them into submodels, pages & steps, and exports the end result as images or PDF. A rich, WYSIWYG UI editor, which provides a fully interactive preview window along side a drag & drop-enabled navigation tree, to help organize and layout your book. Portions of LIC are based on work of Remi Gagne. LIC will be part of the AIOI - LDraw All-In-One-Installer.
Website: github.com/remig/lic#licreator
Utilities
LDConfig Manager 
LDConfig Manager, developed by Michael Heidemann, should allow you to maintain the LDConfig.ldr file by a GUI.
Website: ldraw.heidemann.org/index.php?page=ldconfig-manager
LDFind 
LDFind, developed by Michael Heidemann, should enable you to quick find the part you are searching for. LDFind is part of the AIOI - LDraw All-In-One-Installer.
Website: ldraw.heidemann.org/index.php?page=ldfind
LSculpt 
LSculpt, developed by Bram Lambrecht, is a program which converts a triangle mesh into an LDraw file. The generated model consists of a surface of 1×1 plates oriented in whichever direction provides the best detail. LSculpt is part of the AIOI - LDraw All-In-One-Installer.
Website: code.google.com/p/lsculpt/
LSynth 
LSynth, developed by Don Heyse, is a program that synthesizes bendable parts for LDraw files. The current version 3.1 is based on LSynth 3.0 2004-2009 by Kevin Clague. LSynth is part of the AIOI - LDraw All-In-One-Installer.
Website: lsynth.sourceforge.net/
MPDCenter 
MPDCenter, developed by Michael Heidemann, helps you to maintain all your MPD files. You can check for OMR conformity (only formal not the layout itself of course). You can extract models with all depending files. Change Author, License, Keywords, Theme, History and Filetype (LDRAW_ORG line) on the fly for all LDR files in the MPD. MPDCenter is part of the AIOI - LDraw All-In-One-Installer.
Website: ldraw.heidemann.org/index.php?page=mpdcenter
LDBoxer 
A command-line utility to help you replace LDraw parts with no visible studs or tubes with boxes. Saves rendering time and CPU power. LDBoxer is not part of the AIOI - LDraw All-In-One-Installer.
Website: github.com/Jeremy1980/LDBoxer
Part Author Tools
DATHeader 
DATHeader, developed by Michael Heidemann, it designed to maintain the header of a LDraw part (*.dat) and a tool for reviewing parts on the PT.
Website: ldraw.heidemann.org/index.php?page=datheader
LDCalc 
LDCalc, developed by Michael Heidemann, is a tool for calculation of angles and line intersections. It is also a converter between mm and LDU and inch and LDU or vice versa.
Website: ldraw.heidemann.org/index.php?page=ldcalc
LDPartEditor 
LDPartEditor, developed by Nils Schmidt, is a platform independent CAD tool for LDraw parts.
Website: sourceforge.net/projects/partcreator/
LDPatternCreator 
LDPatternCreator, developed by Nils Schmidt, is a vector based development tool for textured LDraw parts.
Website: sourceforge.net/projects/patterncreator/
LDStructure 
LDStructure, developed by Michael Heidemann, is a tool for analyzing ldraw parts library. With LDStructure you will get a tool that tells you which parts are required to show the current part and where the current part is used in. You will get this information within a second or even quicker. So this tool is a "needs to have" if you are working on parts for the ldraw part library.
Website: ldraw.heidemann.org/index.php?page=ldstructure
PrimGen2 
PrimGen2, developed by Michael Heidemann, based on PrimGen, creates defined primitives that are used in part files.
Website: ldraw.heidemann.org/index.php?page=primgen2
stl2dat 
stl2dat, developed by Marc Klein, is an utilitary tool to convert .stl files issued from cad software like Solidworks, Autocad, and many others to .dat files for ldraw compatible programs.
Website: marc.klein.free.fr/lego/stl2dat/stl2dat.html
txt2dat 
txt2dat, developed by Ross Crawford, is a utility to produce virtual stickers. It allows you to choose any scalable typeface, and create a LDraw file containing a representation of any string in that typeface.
Website: www.br-eng.info/my-lego-roscomenu-29/my-ldraw-roscomenu-45/50-txt2dat