Free Online STL Viewer

View any STL file in 3D. Place it in AR at real scale. Works in your browser — iPhone and Android.

STL (stereolithography) is the most common file format for 3D printing. Every slicer, every printer, every design tool exports STL. But viewing them without downloading a slicer or desktop app has always been painful.

GeometryViewer opens STL files directly in your browser. Drag and drop, or click to open. The model appears in 3D immediately. On your phone, tap "View in AR" to place it in your room at real scale — perfect for checking proportions before you print.

Both ASCII and binary STL formats are supported. The parser runs entirely in the browser with no upload to a server.

Use cases

• Check model scale before printing
• Share a preview link with clients
• Verify geometry without opening a slicer

Need 3D models to view? ModelDirectory.org has thousands of free STL, OBJ, GLTF, and 3MF files — open any of them here in one click.