The short answer
If you just want to look at a GLB, STL, OBJ or FBX file right now, use a viewer that reads the file inside your browser. The one below is the TRELLIS.2 3D viewer: drop a file and orbit it. It opens GLB, GLTF, OBJ, STL, FBX, PLY, VOX, 3DM, 3MF and USDZ files up to 50 MB, and the file is not uploaded.
Everything runs in your browser - no uploads or servers.
That is our own tool, so read the rest of this page as a comparison written by an interested party. Every claim about another product below comes from that product's public page or documentation as of October 2026. We did not score anything, and there is no star rating here, because a viewer is either right for your file and your privacy needs or it is not.
How people actually ask this
The question usually arrives as "how do I open a GLB file online", "free STL viewer no download" or "what can open an FBX without Blender". Behind each one are the same four questions, and they decide the pick:
- Format. Does it open the file you have, or only glTF?
- Upload. Is the file read in the browser, or sent to a server first?
- Account. Do you have to sign in before you see anything?
- What it is for. A quick look, a validation report, editing, or sharing a link with a client?
Six free options compared
| Tool | Formats | File leaves your device? | Sign-in | Best for |
|---|---|---|---|---|
| TRELLIS.2 3D viewer | GLB, GLTF, OBJ, STL, FBX, PLY, VOX, 3DM, 3MF, USDZ | No | No | A quick look at a mixed set of files |
| Online 3D Viewer (3dviewer.net) | Broad, including CAD formats such as STEP and IFC | No | No | Opening unusual or CAD formats |
| glTF Viewer by Don McCurdy | glTF and GLB | No | No | Checking a glTF file against the spec |
| three.js editor | Many mesh formats | No | No | Light edits and re-exporting in a browser |
| Autodesk Viewer | Many CAD and design formats | Yes, to Autodesk's cloud | Yes | Reviewing DWG, RVT or STEP files with a team |
| Blender | Almost everything | No (desktop app) | No | Full inspection, rigs, animation and editing |
TRELLIS.2 3D viewer (this site)
- What it does well: one drop zone for ten formats, including 3MF and USDZ, which many web viewers skip. It centres and scales the model so you see it immediately. It previews PBR materials when the file carries them.
- Limits: 50 MB per file. It is a viewer: it does not slice, measure walls, repair meshes or play FBX animation. A format-specific page exists for each type, for example the STL viewer and the FBX viewer.
- Evidence you can check: the supported formats and the 50 MB limit are printed on the tool page itself, and you can open your browser's network panel while loading a file to confirm nothing is uploaded.
Online 3D Viewer
An open-source browser viewer at 3dviewer.net, with its source on GitHub as Online3DViewer. Its format list is the widest of the browser tools here and includes CAD formats such as STEP, IGES and IFC. Files are read locally. Pick it when your file is something none of the mesh-focused viewers will open.
glTF Viewer by Don McCurdy
At gltf-viewer.donmccurdy.com. Built for glTF and GLB only, and it shows the output of the Khronos glTF validator next to the model. That makes it the right tool when the question is "is this file valid" rather than "what does it look like". It will not open STL, OBJ or FBX.
three.js editor
The editor at threejs.org/editor imports common mesh formats and lets you move objects, change materials and export again, all in the browser. It is more than a viewer, which also means more buttons between you and a quick look.
Autodesk Viewer
Autodesk's free online viewer covers a long list of CAD and design formats, which is why teams use it for DWG and Revit reviews with comments. You sign in with an Autodesk account and the file is uploaded to Autodesk's cloud to be processed. For confidential client files, check that this is allowed before you use it.
Blender
Blender is free, open source and installed on your computer. If you need to inspect a rig, scrub animation, read exact dimensions or fix the mesh, nothing in a browser replaces it. It is also the slowest way to answer "is this the right file".
Which one should you use?
- You received a file and want to see it now: a browser viewer. Use the TRELLIS.2 viewer above for GLB, STL, OBJ, FBX, PLY, 3MF or USDZ, or Online 3D Viewer for CAD formats.
- You are shipping glTF to a website or engine: run it through glTF Viewer for the validation report, then look at it in any viewer.
- The file is under NDA: stay with tools that read locally, or a desktop app. Avoid uploading it anywhere you have not checked.
- You need to change something: three.js editor for small edits, Blender for real ones.
- You are about to 3D print: open the STL to reject an obviously wrong file, then trust your slicer for walls and overhangs. Our mesh check before printing walks through that order.
Common problems when a file will not open
The textures are missing. OBJ files keep materials in a separate MTL file and images next to it, and FBX files often reference external images. A browser viewer only sees the file you dropped. Use GLB when you can, because it packs textures into one file, or re-export with embedded media.
The model is lying on its side or is tiny. Tools disagree about the up axis and units. Most viewers rescale to fit the screen, which shows orientation clearly but hides real size. Read dimensions in your slicer or DCC tool.
The file is too big. Browser viewers cap file size to keep the tab stable. Ours stops at 50 MB. Decimate the mesh in Blender or export a lighter GLB for review.
A 3MF opens as plain grey geometry. 3MF is a package that can hold print settings and colours. A viewer shows the mesh; your slicer reads the rest.
From a picture to a file you can view
If you do not have a model yet, the TRELLIS.2 image-to-3D generator turns one image into a textured GLB draft. Open that draft in the viewer above, then use the GLB to STL converter if it is going to a printer. The how-to posts cover each format in detail: open a GLB file, open an STL file, open an FBX file and convert GLB to STL.
FAQ
Is there a free 3D viewer that does not upload my file?
Yes. The TRELLIS.2 viewer, Online 3D Viewer, glTF Viewer and the three.js editor all read the file in your browser. Autodesk Viewer uploads it to Autodesk's cloud.
Which free online viewer opens the most formats?
Online 3D Viewer has the longest list, including CAD formats. For everyday mesh formats plus 3MF and USDZ, the TRELLIS.2 viewer covers ten types from one page.
Can I open a 3D file on my phone?
Yes. Browser viewers work in current mobile browsers with touch controls. Large files load more slowly than on a laptop.
Do I need Blender to open an FBX file?
Not to look at it. A browser viewer shows the mesh. You need Blender, Maya, Unity or Unreal to review rigs and animation clips.
