Why we built STL File Viewer
Most 3D files get created in one tool and used in another. A model is generated, exported as GLB, needs to become an STL for a slicer, then someone asks to see the OBJ — and every one of those steps today usually means installing desktop software, creating an account, or uploading confidential geometry to somebody else's server. STL File Viewer exists to make those small steps instant and safe.
Every viewer and converter on this site runs entirely inside your browser tab. The moment a page has loaded, it needs no server round trip: parsing, rendering, statistics and format conversion all happen locally on your device, using the same WebGL technology that powers modern 3D on the web. When you close the tab, every trace of your file is gone — because nothing was ever transmitted.
What the tools cover
The current toolset covers six formats end to end. Viewers open STL, GLB, OBJ, FBX, PLY and 3MF files with full orbit controls, wireframe and grid modes, animation playback and a statistics panel that reports meshes, vertices, triangles and bounding dimensions. Converters turn 3MF into STL, OBJ into STL, GLB into STL and GLB into OBJ — always with a preview first and a clear notice about what the target format can and cannot store.
We deliberately do less rather than more. There is no account system, no cloud storage, no upload pipeline and no paid tier, because none of those are needed to inspect a mesh or convert a file. That constraint keeps every tool fast, free and private by design instead of privacy as a marketing line.
How the tools are built
The site is a statically rendered web application. Each tool page loads only the parser it needs — the STL viewer never downloads the FBX or 3MF loader — and the 3D engine is Three.js, the most widely deployed open-source 3D library on the web. Files are read with the browser File API and exported as local downloads; the code that runs on this site is the code you can read in our public repository on GitHub.
Being browser-only is also what makes the tools trustworthy for confidential work: product prototypes, client models and NDA projects can be opened here without a data-processing agreement, because there is no data processing on our side to agree about.
Editorial standards
Every guide and FAQ answer on the tool pages is written and reviewed by the STL File Viewer team, and dated so you can see how fresh the information is. When a format has hard limitations — STL cannot store color, GLB animations cannot survive conversion to a static format — we state them plainly next to the convert button rather than in fine print.
If you find an error in a guide or a file that a tool handles incorrectly, we want to hear about it. The contact page lists the fastest ways to reach the team and to report issues publicly.