# Free 3D file converter

> Convert STEP, 3MF, OBJ, GLB/glTF, USDZ, Rhino 3DM, PLY, FBX and more to STL, 3MF or OBJ in your browser. Free, no sign-up, and the file is never uploaded.

Source: https://freestlviewer.com/3d-file-converter/  
Updated: October 22, 2026

Drop a STEP, 3MF, OBJ, GLB, USDZ, 3DM, PLY or FBX file and download it as STL, 3MF or OBJ. The conversion runs in your browser — nothing is uploaded. The tool is interactive: open https://freestlviewer.com/3d-file-converter/ and drop a file onto the page.

## What it converts

**Into:** STL (binary), 3MF or OBJ.

**From:** every format the Mes3D viewer opens — STL, 3MF (including Bambu
Studio and OrcaSlicer projects), STEP/STP, OBJ (with its .mtl), glTF/GLB,
USDZ/USD, Rhino 3DM, PLY, FBX, DAE, 3DS, AMF, OFF and Alembic.

## How to convert a file

1. Drop the file on the box above or click **Choose 3D file**. For a `.gltf`
   or an `.obj` with materials, drop the whole folder or a ZIP.
2. Check the summary: triangle count, size in millimetres and whether the mesh
   is watertight.
3. Pick **STL, 3MF or OBJ**.
4. If the file has no unit of its own (STL, OBJ, PLY…), confirm what it was
   exported in — millimetres, centimetres, inches or metres. glTF and USD are
   preset to metres, as their specifications define.
5. Click **Convert and download**. The file is saved like any other download.

The output is always written in **millimetres**, which is what slicers and
most CAD tools assume. Picking the right source unit is how you fix a model
that would otherwise open 25.4 or 1,000 times too small.

## What happens to your model

- **Every part becomes one mesh.** Assemblies, multi-object 3MF projects and
  scenes are merged into a single object at their saved positions.
- **Geometry is kept exactly** as the viewer shows it; nothing is decimated or
  smoothed.
- **CAD files are triangulated.** STEP and Rhino geometry is converted to
  triangles once, at a fine tolerance; the result is a mesh, not editable CAD.
- **Colours:** solid colours are kept in 3MF output; textures, animation,
  lights and cameras are not carried over.

## Choosing the output format

| | STL | 3MF | OBJ |
| --- | --- | --- | --- |
| Opens in every slicer | Yes | Modern slicers | Most |
| Records units | No | Yes (mm) | No |
| Colours | No | Solid colours | No |
| File size | Largest | Smallest (compressed) | Medium |
| Best for | Sending to anyone | Your own printing workflow | Modelling and rendering tools |

## On a phone

The converter works in mobile browsers too; the converted file lands in your
Downloads or the Files app. To measure, cut or resize a model on the phone
before printing, and view it in AR, use the Mes3D app for iPhone, iPad, Mac and
Android.

## Frequently asked questions

### Is this 3D converter really free?

Yes. Converting is free on every device, with no account, no watermark and no file-count limit. Files up to 200 MB can be converted.

### Are my files uploaded to a server?

No. The file is read, converted and written by your own browser, and the download is created on your device. That makes it suitable for confidential client work and unreleased designs.

### Which output format should I choose?

STL if you are sending the model to a slicer or anyone you are unsure about — everything reads it. 3MF if you want a smaller file that records millimetres and keeps colours. OBJ for modelling and rendering tools that prefer it.

### Does the converter keep colours and textures?

Solid colours carry over to 3MF output — 3MF and Rhino colours, STEP body colours, OBJ material colours, glTF base colours and PLY vertex colours. Image textures are not carried over, and STL and OBJ output contains geometry only.