3D Model Viewer & Converter (STEP, STL, OBJ, FBX)
View STEP, IGES, STL, OBJ, FBX, 3DS, GLTF and more in your browser, then export to GLB, OBJ, STL or PLY. No uploads.
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A 3D model viewer lets you open and inspect a three-dimensional file without installing CAD software or a modelling suite. This tool renders your model directly in the browser with WebGL: rotate it with the mouse, zoom into details, toggle wireframe mode to inspect the topology, and read basic statistics such as triangle count and bounding-box dimensions. It opens the most common formats used across engineering and 3D graphics, including STEP and IGES (the exchange formats used by parametric CAD packages such as SolidWorks, Fusion 360, CATIA and FreeCAD), STL and OBJ (the workhorses of 3D printing), FBX and Collada DAE (common in game development and animation pipelines), glTF and GLB (the modern web standard), plus 3DS, PLY, 3MF, AMF and VRML.
Frequently asked questions
Is my 3D model uploaded to a server?
Which 3D formats can I open?
Which formats can I convert to?
Can I convert STEP to STL for 3D printing?
Can this tool open SketchUp (.skp) files?
Why does my STEP file export as a mesh instead of exact geometry?
Why does my model appear grey or without textures?
What is the difference between STL, OBJ, GLB and PLY?
How large a file can I open?
Does the viewer work offline?
About 3D Model Viewer & Converter (STEP, STL, OBJ, FBX)
Beyond viewing, the tool also converts. Once a model is loaded you can export it to GLB, OBJ, STL or PLY, which covers the most frequent real-world conversions: turning a STEP assembly into an STL ready for slicing and 3D printing, converting an old 3DS or FBX asset into a modern self-contained GLB for a web page or game engine, or extracting a mesh from a Collada scene as OBJ for further editing in Blender. STEP and IGES files describe exact mathematical surfaces (BREP geometry), so opening them involves tessellation: the precise surfaces are triangulated into a mesh. That work is done by OpenCascade, a full industrial CAD kernel compiled to WebAssembly, which downloads on first use and runs entirely on your machine.
Everything happens locally in your browser. The file you open is never uploaded to a server, which matters for CAD data more than for most file types: mechanical designs, product enclosures and unreleased prototypes are frequently confidential, covered by NDAs or export-control rules. A viewer that works offline once loaded, and that provably cannot leak your geometry, removes that whole category of risk. There is no account, no file-size tier and no watermark.
A few limitations are worth knowing up front. Conversion output is always a triangle mesh, so exporting a STEP file to STL is a one-way trip: the parametric surface definitions, feature history and exact dimensions of the original BREP model are not preserved, and the tool cannot write STEP or IGES. Formats that reference external files (an OBJ with a separate MTL, a glTF with external textures, an FBX pointing at image files) load with their geometry intact but with plain colours instead of textures; the self-contained GLB format avoids this entirely. Very large models are limited by browser memory, so assemblies with many millions of triangles may be slow or fail to load.
From Punched Cards to WebAssembly: How CAD Files Learned to Travel
The oldest format this viewer opens predates the web itself. IGES (Initial Graphics Exchange Specification) was published in 1980 under the sponsorship of the US Air Force and the National Bureau of Standards, born of a very practical military problem: defence contractors all used different CAD systems, and the Pentagon was tired of paying for the same part to be redrawn at every company boundary. IGES files are still structured as 80-column records, a direct inheritance from punched cards. Its intended successor, STEP (ISO 10303), began development in 1984 and took a decade to publish its first release, earning it the joke that STEP stands for Standard for the Exchange of Product data, Eventually. Despite the slow start, STEP won: it is the lingua franca of mechanical engineering today, and the AP242 edition remains under active development.
STL has a stranger origin. Created in 1987 by the Albert Consulting Group for 3D Systems, the company that invented stereolithography, it was designed to feed one specific machine, the first commercial 3D printer. The format is famously crude: a bag of triangles with no units, no colour, no topology, and even a redundant per-facet normal that consumes a third of every binary record. Every attempt to replace it (AMF in 2011, 3MF in 2015, both supported by this viewer) has struggled against its sheer ubiquity. Nearly four decades later, the format built for one machine still moves most of the world's 3D-printing data.
That a full industrial CAD kernel now runs inside a browser tab is its own historical arc. OpenCascade, the engine this tool uses to read STEP and IGES, descends from Euclid, a French CAD system first developed in the late 1970s and used to design parts of the Ariane rocket and Dassault aircraft. Its owner, Matra Datavision, open-sourced the kernel in 1999 after concluding it could not compete selling CAD seats. Two decades later, Emscripten and WebAssembly made it possible to compile those million-plus lines of C++ to run, sandboxed and at near-native speed, on any device with a browser, turning what was once a workstation-class licence purchase into a page load.