STL Files:

STL (an abbreviation of “stereo-lithography”) is a file format native to the stereo-lithography CAD software. Nowadays STL files are widely used within 3D-Printing technology.

Please note:

This project is currently flagged as experimental.

  • The viewer is implemented as a web-application which emulates a local web-server.
  • Known problem so far: The application has a memory limit, which might be reached quite soon. In other words: when trying to view STL-files bigger than appr. 40Mb will possibly crash the viewer.


As there is no build-in support to preview STL files for the Windows-Explorer (as far as I know…), I implemented this utility program for only this reason.

  • The software is self dependent and consists of one single executable.

  • The program emulates a local web server and therefore requires an up-to-date web browser installation (iExplorer, Safari, etc…).

  • The STL-Viewer itself is implemented with jquery.js and three.js.



The software is open source, please feel free to download the source for whatever reason. Any kind of feedback or suggestion whatsoever is welcome.

Special thanks to:


Beside the source code, there is also a binary available for windows, which can be downloaded from here:

Installation notes & usage:

  • The binary is self-independent, does not need to be installed, just copy the executable in a directory or onto your desktop (or create a link onto your desktop).

  • After that, execute the program and drag&drop an STL file onto the application window. Depending on the file size, it might take to get the geometry displayed on the screen.

  • Note: As the web server which controls the STL-Viewer is running locally on your PC, there is no hidden or uncontrolled file transfer to somewhere outside - thus your data is save. If there is any doubt, one might re-build the executable from the available sources.

License & permission to use:

(c) 2018, Johann Oberdorfer - Engineering Support | CAD | Software

This software is distributed under the BSD license. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the BSD License for more details.

Have fun.