View STL files in your browser
The format of 3D printing, a model as a skin of triangles. Open one right here and check it before you print it, with nothing to install. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your model opens in 3D, lit and framed, its size in millimeters, with its objects beside it and what you pick on the other side.
- Its size in millimeters • Read an STL as inches
- Section • Cut it at any height to see inside
- Every object and plate • Hide one or see it alone
- Export • PNG, STL, OBJ, GLB and USDZ
About STL
3D Systems made STL in 1987 for the first 3D printer, the SLA-1, and every slicer and printer has read it since. Thingiverse, Printables and MakerWorld are full of them, and every CAD app saves one.
An STL keeps only the surface of a model, as a list of triangles, in text or, far more often, in binary. It keeps no units, colors or parts: slicers read its numbers as millimeters, though some apps save inches.
Filepeek reads the file in your browser and shows the model lit and framed on a soft shadow, with its size in millimeters, or in inches with Read as inches. Turn it, measure between points that snap to its corners, cut through it at any height with Section, look at it in clay, wireframe or X-ray, and save it as STL, OBJ, GLB or USDZ, or the view as PNG.
Stereolithography
.stl
Format
- MIME type
- model/stl
- Made by
- 3D Systems
- Released
- 1987
Inside the file
- Triangles
- The surface, each with three corners and a normal
- Size
- Millimeters to most slicers, with no unit saved
- Header
- 80 bytes in a binary STL, often naming its app
- Solids
- One or more in a text STL, each named
Opens in every browser
Browsers download STL files, and a slicer or a CAD app is the usual way to see one. Filepeek opens them in Chrome, Edge, Firefox and Safari, text or binary, on any device.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Questions
How do I open an STL file without a slicer?
Drop it on this page or choose Peek an STL. It opens at once in 3D, lit and framed, with nothing to install.
How big will it print?
Its size shows in Inspect and in Show details, in millimeters, which is how slicers read an STL. A model made in inches looks 25.4 times too small, and Read as inches shows its real size.
Can I measure it?
Yes. Choose Measure and click two points on the model. Each snaps to the nearest corner, and the length shows on the line, with its run along each axis.
Can I see inside it?
Yes. Choose Section to cut through the model along X, Y or Z, and drag the slider to move the cut. What it cuts open shows flat, so you see how thick its walls are.
Can I turn an STL into an OBJ or a GLB?
Yes. Choose Export to save it as OBJ, GLB or USDZ, or again as a binary STL, and the view as PNG.
Is my file uploaded?
No. The model opens inside your browser and never leaves your device.