Free Online 3MF Viewer

View 3MF files in 3D with multi-part assemblies, colours, and materials. Preview your 3D prints without installing a slicer. No account, completely free.

What is 3MF?

3MF (3D Manufacturing Format) is an open standard designed specifically for 3D printing. It was created by the 3MF Consortium, an industry group founded by Microsoft and joined by HP, Autodesk, Stratasys, 3D Systems, Materialise, Dassault Systemes, and other major players in additive manufacturing. The format was built to replace STL as the standard file format for 3D printing workflows.

A 3MF file is a ZIP archive that contains XML documents describing the 3D model along with any associated resources. The core XML defines triangle mesh geometry with vertex positions and triangle indices. Unlike STL, which stores redundant vertex data for every triangle, 3MF uses an indexed mesh structure that is both smaller and faster to parse. The specification requires that meshes be manifold (watertight), which eliminates an entire class of printing errors before the file ever reaches a slicer.

Beyond basic geometry, 3MF supports features that STL cannot represent at all. Per-vertex and per-triangle colours allow full-colour models for multi-colour printers like the Bambu Lab X1 with AMS. Material assignments define which regions of a model should be printed in which material, enabling multi-material prints from a single file. Texture mapping wraps 2D images onto 3D surfaces for photorealistic full-colour printing on powder-bed systems.

3MF also stores print-specific metadata that other formats ignore. Build platform layout defines how parts should be arranged on the print bed. Component hierarchies describe multi-part assemblies where each component can have its own transform, material, and colour. Print tickets can store slicer settings like layer height, infill density, and support configuration, making the file a complete record of the intended print job.

The format uses standard ZIP compression, so 3MF files are typically 50-80% smaller than equivalent STL files. Combined with the indexed mesh structure and elimination of redundant vertex data, 3MF is the most efficient mesh format for 3D printing by a significant margin.

3MF vs STL

STL has been the default format for 3D printing since the 1980s, but it has fundamental limitations that 3MF was designed to address. Understanding the differences helps explain why every major slicer and CAD tool now supports 3MF as its primary format.

Geometry representation. STL stores each triangle independently with three vertex coordinates, meaning shared vertices between adjacent triangles are duplicated. A model with 100,000 triangles stores 300,000 vertices even though the actual mesh may have only 50,000 unique vertices. 3MF uses an indexed mesh where vertices are stored once and triangles reference them by index. This produces smaller files and faster parsing.

Mesh integrity. STL files frequently contain non-manifold edges, degenerate triangles, flipped normals, and gaps between triangles. These errors cause slicing failures, missing geometry, and failed prints. 3MF requires manifold meshes by specification. If a 3MF file validates, its mesh is guaranteed to be watertight and printable.

Colour and material. STL has no concept of colour or material. Some tools use a non-standard vertex colour extension, but it is not part of the specification and support varies. 3MF natively supports per-vertex colour, per-triangle colour, material assignments, and UV-mapped textures. Multi-colour and multi-material prints are defined cleanly in a single file.

Metadata and print settings. STL contains nothing beyond geometry. 3MF can store build platform layout, print tickets with slicer settings, component hierarchies for assemblies, and custom metadata. When you save a project in PrusaSlicer or Bambu Studio, the 3MF file contains everything needed to reproduce the exact print.

For a deeper comparison, read our guide on STL vs 3MF.

How to View 3MF Files Online

Viewing a 3MF file in GeometryViewer takes three steps:

• Step 1: Open your file. Drag and drop a .3mf file onto the viewer above, or click the "Open .3mf file" button to browse your device. The file is decompressed and parsed entirely in your browser.
• Step 2: Inspect the model. Orbit, zoom, and pan with mouse or touch to examine the model from every angle. Multi-part assemblies display with each component in its correct position. Colours and materials render as defined in the file. Check geometry, verify part alignment, and confirm the model looks correct before printing.
• Step 3: Preview for printing (optional). Use the viewer to check for visual issues before sending the file to your slicer. Verify that multi-part assemblies are correctly aligned, colours are assigned to the right regions, and the overall model matches your design intent.

No slicer installation is required. GeometryViewer runs in any modern browser on desktop or mobile. Your file is never uploaded to any server. For more detail on opening 3MF files without slicer software, see our guide on how to open 3MF without a slicer.

Preview Your 3D Print

GeometryViewer is particularly useful as a quick preview tool before committing to a print. Opening a slicer takes time, especially for complex models. GeometryViewer loads instantly in your browser and shows you the model geometry, colours, and multi-part assembly layout within seconds.

Use it to verify that exported 3MF files contain the correct geometry before transferring them to your printer. Check that multi-colour assignments are correct before loading filaments. Confirm that assembly components are in the right positions before starting a multi-hour print.

For advanced print preview features including layer-by-line simulation, material visualisation, and build volume checking, see our dedicated 3D print preview tool.

Compatible Software

3MF is supported by every major slicer, CAD application, and 3D printing platform. Here are the tools that import, export, or work with 3MF files:

• PrusaSlicer -- Uses 3MF as its native project format. Saves all slicer settings, part arrangement, modifier meshes, and multi-material assignments in the 3MF file. Importing a PrusaSlicer 3MF project restores the complete print configuration.
• Cura -- Ultimaker's slicer supports 3MF import and export. Project files use 3MF as the container format, preserving per-model settings, build plate layout, and extruder assignments for multi-material printers.
• Bambu Studio -- The default slicer for Bambu Lab printers. Uses 3MF exclusively for multi-colour and multi-material prints with the AMS system. Colour painting and material assignments are stored directly in the 3MF file.
• Simplify3D -- Imports 3MF files with geometry and colour data. Supports multi-part models where each component can be assigned different process settings.
• SolidWorks -- Exports 3MF natively with full geometry, colour, and material support. 3MF is one of the recommended formats for transferring designs from SolidWorks to 3D printers.
• Fusion 360 -- Autodesk's CAD platform exports 3MF with mesh geometry and component structure. The 3MF export preserves body colours and component hierarchy from the Fusion 360 design.

Privacy

GeometryViewer is a fully client-side application. When you open a 3MF file, it is decompressed and parsed entirely in your browser using JavaScript and WebGL. The file is never uploaded to any server. There is no backend processing, no cloud storage, and no tracking of file contents.

This means you can safely preview proprietary designs, client files, and unreleased products without any risk of data exposure. The viewer works offline after the initial page load. No account or registration is required to use any feature.

Frequently Asked Questions

Need 3D models to view? ModelDirectory.org has thousands of free STL, OBJ, GLTF, and 3MF files — open any of them here in one click.