Stud.io / LDD / LDraw — digital LEGO design

For MOC design and instruction creation AFOLs use digital software instead of physical bricks. Three programmes dominate:

Stud.io (BrickLink)

The current standard, free, from BrickLink (which makes it LEGO-owned). Fully 3D, supports most of the current LEGO catalogue, and can auto-generate instructions in PDF format. Want to sell a MOC on Rebrickable or BrickLink? You design in Stud.io.

LDD — LEGO Digital Designer

LEGO's own design software from 2004 onwards. In 2022 LEGO pulled the plug; no more updates, but the existing version still works. Many older MOCs are saved as .lxf files (LDD format) and remain openable.

LDraw

Open-source project started in 1995, with the largest free LEGO parts database. Various editor applications build on it: LDCad (Windows), Bricksmith (Mac), MLCad. For "purists" — more technical, less polished — but unbeatable in completeness.

When which?

• Stud.io: new MOCs, instructions for BrickLink sale — no debate, this is the right choice
• LDraw: archiving, integration with other tools, technical projects
• LDD: only to view old .lxf files; for new work no longer recommended