Free Online STL File Viewer
Drop an STL file and inspect your 3D printable geometry in seconds. Verify mesh quality, measure dimensions, and share review links — right in the browser.
What is a STL file?
STL (Stereolithography) is the most widely used file format for 3D printing and rapid prototyping. Created by 3D Systems in 1987, STL describes a 3D shape as a collection of triangular facets. The format is universally supported by slicer software (Cura, PrusaSlicer, Bambu Studio) and every 3D printer on the market.
What you can do with STL files in CADDaddy
CADDaddy renders STL files using hardware-accelerated WebGL for smooth 60fps navigation, even on dense meshes. Both binary and ASCII STL formats are supported. Once loaded, you can orbit, zoom, pan, toggle wireframe mode, and use section planes to inspect internal geometry.
Instant mesh preview
Open binary and ASCII STL files in seconds. No software to install, no plugins to configure.
Wireframe mode
Toggle wireframe view to inspect triangle density, mesh quality, and potential printing issues.
Pre-print measurement
Verify dimensions with point-to-point measurement before sending to the slicer.
Cross-section view
Slice the model along X, Y, or Z to check wall thickness and internal structure.
Export to GLB
Convert STL to GLB for embedding in web pages, AR apps, or game engines.
Share for review
Send a review link to clients for approval — they see the model without installing anything.
STL Viewer FAQ
What is an STL file?+
STL (Stereolithography) is a file format that describes the surface geometry of a 3D object using a mesh of triangles. It is the most common format for 3D printing and rapid prototyping. STL files come in binary and ASCII variants — CADDaddy supports both.
How do I view an STL file without software?+
CADDaddy opens STL files directly in your browser. Drag and drop your .stl file into the viewer — no install, no account, no plugins. You get full 3D orbit and zoom in seconds.
Can I measure an STL file before printing?+
Yes. CADDaddy's Pro measurement tools let you verify point-to-point distances on your STL model with unit calibration. Confirm dimensions are correct before sending a file to the printer.
What is the difference between STL and OBJ?+
STL stores only triangle geometry — vertices and face normals. OBJ also supports texture coordinates, materials, and vertex colors. For 3D printing, STL is standard. For visualization and rendering, OBJ is more versatile.
Can I convert STL to GLB?+
Yes. CADDaddy can export your STL model as a GLB file, which is the binary form of glTF — the standard format for web 3D, AR experiences, and game engines.
Is there a file size limit for STL viewing?+
Free accounts can view standard-sized STL files. The Pro plan ($19 one-time) supports larger files and complex meshes with smoother performance.
Other formats CADDaddy supports
View your STL file now
No install, no account required. Drop your file and start inspecting.
Open viewer