Open and view STL files online, free. Orbit, zoom and measure the model, check it will print on your printer, then repair or edit it. No install.
Drop in an STL, your own or one you downloaded from Printables, MakerWorld or Thingiverse, to orbit, zoom, X-ray and measure it, free, with no install and no sign-up. Check it fits your printer and will print, and when you want to change something, the same window edits and re-exports it.
Free · Runs in your browser · No account needed
Most online STL viewers only let you spin the model. OwlCAD inspects it and edits it in the same place.
Drag an STL into the browser and it loads on the build plate: orbit, zoom, fit to view, and toggle X-ray to see through the model. Nothing to install.
Measure the model itself: edge length, hole radius and diameter, true arc length, face area, angle, and the smallest gap between two parts. Then read its overall size, volume and triangle count. The numbers you need before you print.
A plain viewer stops at looking. OwlCAD keeps going: scale to exact dimensions, combine with other shapes, repair non-watertight geometry (holes your slicer can’t fill), and re-export.
STL, 3MF, OBJ, GLB and STEP all open here, plus 2D SVG and DXF, with units detected on import so every model loads at the right size.
An STL is just a triangle mesh, so almost nothing on a fresh computer opens one, which is why "what do I open this with?" is the commonest question about the format. In a browser, the answer is nothing at all.
Drag the .stl onto the build plate, or click to choose it. Your browser reads the file itself, so there is no upload to wait for, no queue, no account, and no program to install first. It works the same on Windows, macOS, and Linux, because it is a web page.
Orbit, zoom, and fit to view; switch on X-ray to see through the walls. Then measure the model itself: an edge, a hole’s radius and diameter, an arc’s true length, a face’s area, an angle, or the gap between two parts. It reads out overall size, volume and triangle count too.
If the file is the wrong size, reinterpret its units in one click. Run the print check to see whether it fits your printer and where it has overhangs or thin walls, and repair the mesh if it is broken. If it needs changing, scale, cut or combine it, then export STL or 3MF for Bambu Studio, PrusaSlicer, Cura or OrcaSlicer, or OBJ or GLB for other tools.
It opens on your device, it is saved to your workspace as you work, and it exports back out in the format your slicer wants.
Your browser reads and renders the model itself, so it appears as soon as you drop it in — you are never queued behind anyone else’s upload, and the file does not travel anywhere before you can see it.
Most online viewers forget your file the moment you close the tab. OwlCAD keeps the model in your own workspace and syncs it as you work, so it is still there when you come back to this browser. Create a free account and it follows you to any device, and your projects dashboard lets you delete anything you no longer want.
When you are done, export STL, 3MF, OBJ, GLB or STEP — the format your slicer or your colleague actually needs, not a project file that only opens here.
View it, measure it and edit it, all in the browser, with no download.
Yes. Drag an STL into the browser and view it in 3D for free, with no install and no sign-up. Orbit, zoom, fit to view, and switch on X-ray to see inside the model.
Yes. OwlCAD runs entirely in your browser. Drop in a .stl and inspect it immediately: rotate it, measure its edges, radii, arcs, face areas, and gaps, and read its overall size, volume, and triangle count.
Yes. Unlike a plain viewer, OwlCAD is a full editor. Once your STL is open you can scale it to exact dimensions, combine it with other shapes, repair non-watertight geometry (holes or inside-out faces a slicer can’t fill), and export it again.
STL, 3MF, OBJ, GLB and STEP, plus 2D SVG and DXF, with units detected on import, so a model always loads at the right size.
An STL records no units, so a part authored in inches arrives 25.4× too small and one authored in metres arrives far too large. The bar shown on import reinterprets the file as millimetres, centimetres, inches, or metres in one click and previews the resulting dimensions each time, so you can see which reading is right before accepting it.
Open this page and drag the .stl onto the build plate. That is the whole procedure. There is nothing to install and no account to create, because your browser reads the file directly on your device. It behaves identically on Windows, macOS, Linux, and ChromeOS, since it is a web page rather than an application.
On the desktop, a slicer (Cura, PrusaSlicer, Bambu Studio), a CAD package (Fusion 360, FreeCAD, SolidWorks), or a bundled viewer such as Microsoft 3D Viewer will each open one, but all of them are installs, and most do far more than you need if you only want to look. A browser tool skips that entirely: OwlCAD opens the file in the tab you already have, and unlike a plain viewer it will also measure, repair, and edit it.
No. Nothing installs, and there is no upload to wait for: the file is read locally by your browser, so it is on screen before anything syncs. That also means no file-size queue and no waiting on someone else’s upload.
Because an STL is only a list of triangles with no application associated to it, so a fresh install of Windows or macOS has nothing registered to handle the extension and offers to search the store instead. The file is almost certainly fine; it just needs something that understands meshes, which is what this page is.