What is an LDR file?
The .LDR extension primarily identifies an LDraw Model File. These files store 3D models of virtual LEGO creations. The LDraw.org open standard defines this format. Users build and share these models using CAD programs like LeoCAD and LDCad. The .LDR file contains plain text that defines the 3D coordinates, colors, and part numbers for each individual LEGO piece.
Other LDR Formats
The .LDR extension also has several other technical uses. It can be a firmware loader for Analog Devices Blackfin processors, a LiDAR point cloud data file from DJI Zenmuse L2 systems, or an application data export from Appian software. The Appian exports are often structured as .ZIP archives. In rare cases, .LDR files are structural analysis project files from STA4CAD, PLC ladder logic programs, or simple .JPG images used in specific business software.
How to open LDR files?
You can open standard LDraw Model Files with 3D modeling software like LeoCAD. Because they are text-based, you can also view the raw data using Notepad++ or standard system text editors. If your file is an Appian export, standard archive tools like WinZip or 7-Zip can extract the contents.
Identify your file
Because the .LDR extension has multiple possible meanings, you can use viewer.online/ldr to identify the exact format and creator software. Our tool lets you inspect the file structure, extract readable text, and check whether an online preview is available.
Summary
viewer.online/ldr is extremely useful for identifying, inspecting, and understanding .LDR files without installing software or dealing with compatibility problems.