# Free online 3MF viewer

> Open any .3mf file in your browser, including multi-part Bambu Studio and OrcaSlicer projects. Free, no upload, no sign-up — the file never leaves your device.

Source: https://freestlviewer.com/3mf-viewer/  
Updated: October 22, 2026

Drop a .3mf file to see every part in place, including Bambu Studio and OrcaSlicer projects, with the colours stored in the file. Nothing is uploaded. The tool is interactive: open https://freestlviewer.com/3mf-viewer/ and drop a file onto the page.

## What a 3MF file actually is

A 3MF file is a ZIP archive. Inside it are XML "model parts" that hold the
triangle meshes, plus relationship files that say which part is the main one,
and optional extras such as thumbnails, textures and slicer settings. The
format is maintained by the 3MF Consortium, and unlike STL it records the unit
of measurement, colour and material assignments, and how several objects are
placed relative to each other.

That richness is why "it opens in my slicer but not in this viewer" is a
common complaint. Many general 3D viewers read only the simplest layout: one
model part with all the meshes in it. Real-world printing files often look
different.

## Why Bambu Studio and OrcaSlicer files break other viewers

Bambu Studio and OrcaSlicer save projects using the 3MF **Production
extension**. Each object's mesh lives in its own file under `3D/Objects/`, and
the main model part refers to those files through components with a `p:path`
attribute. Every one of those object files declares its own object with id
`1`, so a reader that keys objects by id across the whole archive mixes them
up — or finds nothing at all.

Mes3D follows the package the way the specification intends:

- it finds the root model part from the package relationships (falling back to
  `3D/3dmodel.model`);
- object and material ids are scoped to the file that declares them;
- components and build items are followed across files through `p:path`, with
  their transforms applied;
- the model's declared unit is converted to millimetres;
- when there is no usable build section, the top-level objects are shown
  instead of an empty scene.

The result is that a multi-part project opens with every part where the slicer
had it.

## Colours

Colours are read from the 3MF's standard base materials and colour groups and
applied per triangle, falling back to the object's default colour. Switch the
model colour to **Original** in the toolbar to see them; any other colour
choice overrides them so you can inspect the shape on its own.

One caveat for multi-colour printing: Bambu Studio and OrcaSlicer store the
regions you paint for the AMS, and which filament each object uses, in their
own project data rather than as 3MF colour groups. Those choices are not
shown — the geometry is, so you can still check every part before printing.

## "This 3MF only contains G-code"

When you export a **sliced** plate from Bambu Studio or OrcaSlicer, the 3MF
you get (often named `.gcode.3mf`) is a print job. It holds the toolpaths as
`Metadata/plate_N.gcode`, and frequently not the geometry you modelled. A viewer
that does not check for this simply shows nothing.

Mes3D detects this case and says so. The fix is to open the project file you
saved from the slicer (**File → Save Project**), not the exported print file.

## How to open a 3MF file here

1. Drag the `.3mf` file onto the drop zone above, or click **Choose 3D file**.
2. The model opens full screen. Drag to rotate, scroll or pinch to zoom, and
   right-drag or two-finger drag to pan.
3. Use the preset views (front, top, side…) and switch between perspective and
   orthographic projection to check alignment.
4. On a computer, click two points to measure the distance between them in
   millimetres, or open the analysis panel for volume, surface area, estimated
   print weight, watertightness and overhang ratio.

Everything runs in your browser. The file is read from your disk into memory
and never sent to a server, which matters when the model is client work or an
unreleased product.

## 3MF compared with STL for printing

| | 3MF | STL |
| --- | --- | --- |
| Units | Stored in the file | Not stored — the receiver guesses |
| Colour and materials | Yes | No |
| Several objects with placement | Yes | One undivided triangle list |
| Slicer settings | Optional, in the package | No |
| File size | Compressed ZIP | Uncompressed, ~50 bytes per triangle (binary) |
| Support | Modern slicers and CAD | Everything |

If you are sending a model to someone with a modern slicer, 3MF loses less
information. If you do not know what they use, STL is still the safe fallback.

## On a phone

In a mobile browser the viewer handles opening, rotating, zooming and the
dimensions panel. The Mes3D app for iPhone, iPad and Android opens 3MF files
from Files, Mail or a download with one tap, and adds measuring, mesh analysis
and cross-sections, plus exporting a resized or cut model back to 3MF with
its colours. On iPhone and iPad it also lets you place the model in AR, and
once it is installed, `.3mf` files show a 3D preview and thumbnail right in the
Files app.

## Limits

- Files up to 200 MB open in the browser; very large multi-plate projects can
  take a few seconds to assemble.
- Textures stored in a 3MF are not displayed; per-triangle colours are.
- Slicer-only data such as supports, seams and modifier volumes is not drawn —
  this is a model viewer, not a slicer preview.

## Frequently asked questions

### Can I open a Bambu Studio 3MF without Bambu Studio?

Yes. Mes3D reads Bambu Studio and OrcaSlicer project files in the browser and shows every object at the position it was saved in. You do not need the slicer installed, and the file is not uploaded anywhere.

### Why does my 3MF say it only contains G-code?

A sliced print job exported from Bambu Studio or OrcaSlicer (often named .gcode.3mf) stores the toolpaths as plate_N.gcode files and may not include the model geometry at all. Mes3D recognises that case and tells you so; open the project 3MF you saved from the slicer instead.

### Does the viewer show 3MF colours?

Colours written as standard 3MF base materials or colour groups are shown per triangle. Bambu Studio and OrcaSlicer keep painted multi-colour regions and per-object filament choices in their own project data rather than as 3MF colours, so those parts appear in a single colour.

### What units does a 3MF use?

3MF declares its unit in the file (millimetre by default; micron, centimetre, inch, foot and metre are also allowed). Mes3D converts everything to millimetres, so the dimensions and volume it reports are real sizes.

### Is 3MF better than STL?

For 3D printing, usually yes: 3MF stores units, colours, several objects with their placement and slicer settings in one compressed file, while STL is a bare triangle list with no units. STL is still the most widely supported exchange format.