LDraw is the open file format and community parts library behind most LEGO CAD software. A model is a plain text file listing parts, colors and positions, and a large library of LEGO parts, maintained by volunteers at LDraw.org, supplies the shapes. The quickest start on Windows is the LDraw All-In-One Installer; on any system, LeoCAD is the friendliest editor to begin with.
Quick answer: install the All-In-One Installer (Windows) or LeoCAD plus the parts library (macOS, Linux); build your first model in LeoCAD; move to LDCad when you want more control; make instructions with LPub3D; render with POV-Ray, LDView or Blender.
How LDraw works
An LDraw model is a text file. Each line places one part, by its part number, in a color, at a position and rotation. Files ending in .ldr hold a single model; .mpd files bundle a main model and its submodels in one file. Because the format is open and plain text, every LDraw tool can read every other tool's files, and so can BrickLink Studio, which opens and exports LDraw too.
Installing it
On 64-bit Windows, download the LDraw All-In-One Installer from LDraw.org. Its 2026 release installs the parts library and the LDView viewer by default and offers these optional programs:
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LeoCAD 25.09, an editor.
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LDCad 1.7 Beta 2, an editor.
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LPub3D 2.4.9, for building instructions.
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POV-Ray 3.7 with the LGEO parts library, for photorealistic renders.
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An offline parts catalog, for browsing parts without a connection.
LeoCAD's own site has a newer version, 26.09, released on September 19, 2026. A separate 32-bit installer still carries older tools such as MLCad 3.52 for systems that need them. On macOS and Linux, install LeoCAD, which runs on Windows, macOS and Linux, and add the parts library from LDraw.org.
Choosing an editor
| Editor |
Best for |
Notes |
| LeoCAD |
Beginners, any operating system |
Release 26.09 (September 2026) redesigned undo and redo and added a new rotation gizmo; 25.09 added a train track layout editor and Blender render support. |
| LDCad |
Builders who want fine control |
LDraw.org calls it the newest of the editors and by many considered the most complete; version 1.7 Beta 2 ships in the installer. |
| MLCad |
Older files and systems |
An older editor, still offered as 3.52 in the 32-bit installer. |
Your first model in LeoCAD
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Find a part in the parts list by name or number, and pick its color.
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Drag it into the scene and move or rotate it with the on-screen controls; parts align to the LEGO grid.
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Add steps as you build, so the file already contains the order you would build it in, which matters later for instructions.
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Use submodels for repeated or separate assemblies, saved together in one .mpd file.
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Save as .ldr or .mpd, which every LDraw tool can open.
Instructions with LPub3D
LPub3D reads the steps in an LDraw file, renders each step and lays them out into instruction pages, with parts lists per step and callouts for submodels. Add steps while you build in the editor and LPub3D has far less work to do.
Rendering
LDView gives quick, clean images. For photorealistic renders, POV-Ray with the LGEO library is the classic LDraw route, and LeoCAD can hand a model to Blender for rendering since version 25.09.
Opening LDraw files in a browser
Not everyone who wants to see your model will install an editor. Our LDraw 3D Viewer opens an LDraw file in the browser, lets anyone turn it around in 3D and step through the build, large models included. The LDraw Model Checker lists the model's parts with catalog links, shows which bricks connect and compares two versions of a build.
From file to real bricks
Export or copy the parts list from your editor, then buy the parts. Our parts sourcing guide compares LEGO Pick a Brick, BrickLink and parting out sets. If you would rather work in one program that handles ordering for you, see our BrickLink Studio tutorial.
