A free online STL viewer and 3D viewer
A free online STL viewer and 3D viewer that opens STL files — binary or ASCII — as well as OBJ, GLB, GLTF, PLY, FBX, DAE, AMF and 3MF, straight in your browser. Drop a file in and it is read from your own disk and drawn with WebGL — nothing is uploaded, there is no account and there is nothing to install. Check an STL's real size in millimetres and its triangle count before you print, orbit and zoom around the model, play back any animation it carries, cut through it with a cross-section, separate a multi-part assembly with the explode slider, switch on studio lighting with soft shadows, and save a high-resolution render of what you see.
How to view a 3D file online
No account, no install and no upload. The viewer opens the file on your own device and draws it with WebGL, so it works the moment the page has loaded.
Open your file
Drag an STL, OBJ, GLB, GLTF, PLY, FBX, DAE, AMF or 3MF file onto the viewer, or click to browse for one.
Look around
Drag to orbit, scroll to zoom and right-drag to pan. The camera presets snap to a straight-on front, top or side view.
Inspect it
Read the vertex, face and object counts and the exact bounding box. Wireframe and normals shading show how the mesh is built.
Play and capture
Play any animation the file carries, then switch on Studio lighting and save a high-resolution render of the result.
Shading modes
rendered in this tool
One model under four shading modes. Original uses the file’s own materials; Solid replaces them with a flat colour so the silhouette and topology read clearly; Normals colours every face by the direction it points, which makes inside-out faces obvious at a glance; Wireframe shows the triangles themselves.
Why use this 3D viewer
Built for the moment you have a model and just need to see it — before you print it, send it on, or decide whether it is worth opening a full 3D package for.
Your files stay with you
The model is read straight from disk and rendered locally. Nothing is transmitted, which is also why it keeps working with the network off.
Nine formats, one page
STL, OBJ, GLTF, GLB, PLY, FBX, DAE, AMF and 3MF all open in the same place, including Draco-compressed and KTX2-textured glTF.
Animation playback
Rigged and animated models play back in the browser. Pick a clip, scrub the timeline and change the speed.
Studio lighting
Image-based lighting, soft shadows and filmic tone mapping turn a flat preview into something you can put in front of a client.
Real numbers
Bounding-box dimensions, vertex and face counts, material and texture totals — the figures that decide whether a model will slice well.
Free, with no signup
No account, no watermark, no file-size ceiling beyond what your own device can hold in memory.
Studio lighting
rendered in this tool
Studio lighting is on by default. Switch it off and the model is lit by the scene alone — flatter and darker, but closer to the file’s own materials, which is what you want when you are judging someone else’s model rather than presenting your own.
3D file format guide
Formats disagree about what they store. If a model opens but looks wrong, the reason is usually in this table.
| Format | Carries | Worth knowing |
|---|---|---|
| STL | Geometry only | No colour and no unit of measurement. The default for 3D printing. |
| OBJ | Geometry, UVs | Materials live in a separate .mtl file, which a single dropped file cannot reach. |
| GLTF / GLB | Everything | Materials, textures, rigs and animation. Measured in metres, so a 1.8 m figure reads as 1.8. |
| PLY | Geometry, vertex colours | Common output from 3D scanners and photogrammetry. |
| FBX | Geometry, animation | Must be version 2013 or newer — older binary FBX uses a container browsers cannot read. |
| DAE | Geometry, animation | Collada. An older interchange format, still emitted by many CAD tools. |
| AMF | Geometry, colour | XML-based and largely superseded by 3MF. |
| 3MF | Geometry, colour, units | The modern printing package. Unlike STL it records what a millimetre means. |
What is an STL file?
STL is the most common file format for 3D printing. It describes the outside surface of an object as thousands of small triangles and nothing else: there is no colour, no texture, no material and no unit of measurement. That simplicity is why every slicer and CAD program can read it, and also why an STL sometimes opens at the wrong size or looks plain grey.
STL comes in two flavours. Binary STL is compact and is what most programs export; ASCII STL is plain text, easy to read but several times larger. This STL viewer opens both, and shows the width, depth and height of the model so you can confirm its size before printing.
Five things to check in an STL file
A minute in the STL viewer can save hours of failed printing.
1. The size
Compare the dimensions with the size you expect. A model 25 times too small was exported in inches; 1000 times too big, in metres. Convert the units in one click.
2. Flipped faces
Switch the shading to Normals. Patches that look different from their neighbours point inwards and can cause holes or missing layers when the model is sliced.
3. Thin walls
Drag the cross-section through the model. Walls thinner than about two nozzle widths, roughly 0.8 mm, may not print at all.
4. Hidden insides
The section view also reveals hollow parts, trapped geometry and overlapping shells that are invisible from the outside.
5. Triangle count
Millions of triangles slow a slicer down without adding visible detail. If the count is huge, simplify the mesh before you print.
Then slice it
Happy with the model? Open it in Print Control to orient, scale and slice it to G-code, all in the browser.
Understanding 3D files in the browser
What a 3D file actually contains, and why the same model can look different from one tool to the next.
Geometry is only half the file
Every format stores vertices and the faces joining them, but that is where the agreement ends. Materials, textures, rigs, animation and units are optional extras that some formats carry and others discard entirely. A model that opens as plain grey is usually not broken — the colour was simply never in the file you were given.
Units and scale
glTF and GLB are defined in metres, 3MF records its own unit, and STL and OBJ store no unit at all — a number in the file is just a number. That is why the same object can read as 1.8 in one tool and 1800 in another. Check the dimensions panel against the size you expect before you scale anything.
Materials versus textures
A material describes how a surface responds to light; a texture is an image wrapped onto it. A file can have one without the other. If a model looks white, either no colour map was exported, or it uses the retired specular-glossiness materials that current engines dropped — the viewer detects that case and recovers the texture where it can.
Rigs and animation
An animated model carries a skeleton plus clips that move it, and skinning weights that bind the mesh to the bones. All three have to survive the export. When a rig arrives broken, it is almost always because an intermediate tool rewrote the file without carrying skinning through — the original usually still works.
Compression and texture formats
Draco compresses glTF geometry, meshopt compresses vertex data, and KTX2 stores GPU-ready textures. All three need a decoder, which the viewer loads on demand. Without one a file still opens, but arrives stripped — which is why a compressed model can appear untextured elsewhere and correct here.
When you need a full 3D package
A viewer inspects; it does not edit. To remodel geometry, repaint materials, retopologise or author animation you want Blender or a CAD tool. To change format, orient for printing or slice to G-code, the converter and Print Control below do that job without the learning curve.
What people use it for
Checking a download before printing
Open a model from a sharing site and read its real dimensions and face count before committing hours of print time to it.
Reviewing someone else's file
Look at a client or supplier model on any machine without installing Blender, and without uploading their work to a third party.
Checking a rig and its animation
Confirm that clips survived an export, play each one back, and see whether the skinning still deforms the way it should.
Producing a quick render
Frame the model, switch on Studio lighting and save a high-resolution image for a listing, a report or documentation.
When a model does not look right
The handful of things that account for almost every "it opened but it looks wrong" case, and what to do about each.
Nothing appears
The model is probably far off the origin or enormously scaled, so the camera is inside it or a long way from it. Press Reset view, which re-frames whatever was loaded.
It is plain white or grey
No colour survived the export. Check Shading is set to Original rather than Solid, and remember a .gltf that points at separate image files cannot reach them — re-export it as a self-contained .glb.
The surface looks faceted
STL stores no smoothing information at all, so a curved surface arrives as flat triangles. That is the file, not the viewer — export from the original CAD model at a finer tolerance if you need it smoother.
An FBX will not open
Binary FBX older than 6400 (2013) uses a container browsers cannot read. Re-export as FBX 2013 or newer, or run it through the 3D File Converter first.
Parts are inside out
Inverted normals make faces vanish when seen from the front. Normals shading shows the direction of every face — consistent colour means consistent winding.
It is slow to load or orbit
Text formats such as OBJ and ASCII STL parse far slower than their binary equivalents, and a multi-million-triangle scan will tax any device. Try the binary version of the same file first.
Frequently asked questions
The questions that come up most often about viewing 3D files in a browser.
How do I open an STL file online?
Drag the .stl file onto the viewer, or press Open and pick it. It appears in a few seconds, ready to rotate, zoom and inspect. There is nothing to install and no account to create.
Does it open binary and ASCII STL files?
Both. Binary STL is the compact form most programs export; ASCII STL is plain text and much larger, so it takes a little longer to load, but it opens the same way.
Can I measure an STL file?
The viewer shows the model's overall size, width, depth and height, in the dimensions panel, together with its vertex and face count. It does not measure the distance between two points you click.
How do I check an STL before printing?
Confirm the real size in the dimensions panel, switch the shading to Normals to spot faces that point the wrong way, and use the cross-section to look inside for hollow parts or thin walls. Wireframe shading shows how many triangles the model uses.
Can I view STL files on my phone?
Yes. The viewer runs in modern mobile browsers on Android and iPhone. Tap Open and choose the file from your downloads or cloud storage.
Are my files uploaded anywhere?
No. The viewer reads the file directly in your browser and renders it with WebGL. Nothing is sent to a server, so your files stay private.
What file formats can I open?
STL, OBJ, GLTF, GLB, PLY, FBX, DAE, AMF and 3MF. Draco-compressed, meshopt-compressed and KTX2-textured glTF files are decoded as well. FBX must be version 2013 or newer, because older binary FBX uses a container browsers cannot read.
Why can't I see my model's texture?
Usually the file stores its materials in the retired specular-glossiness format, which current 3D engines no longer read. The viewer detects this and recovers the colour texture automatically, telling you when it has done so. If it reports that no colour texture could be applied, check the Shading control in the settings drawer is set to Original rather than Solid, and note that a .gltf referencing separate image files cannot reach them — export a self-contained .glb instead.
Why does my model look tiny or enormous?
Formats disagree about units. glTF and GLB are defined in metres, so a 1.8 m model reads as 1.8 in a millimetre-based tool, while STL and OBJ store no unit at all. Compare the dimensions panel against the size you expect and scale accordingly.
Is there a file size limit?
The tool imposes none. The practical ceiling is your device's memory — very large meshes take longer to parse and render, and text-based formats such as OBJ and ASCII STL are slower than their binary equivalents.
Can I convert or print the file after viewing it?
Yes. The 3D File Converter opens the same formats and exports to STL, OBJ, GLTF, GLB, PLY, FBX and USDZ, and Print Control prepares a model for printing and slices it to G-code.
Related tools
3D File Converter
Convert between STL, OBJ, GLTF, GLB, PLY, FBX and USDZ in the browser, with the same privacy model as the viewer.
Print Control
Orient, scale and repair a model for printing, estimate cost and time, and export G-code without installing a slicer.