STLView

STL Simple Viewer is a great app to quickly view 3D STL files. Supports both ASCII and Binary STL files. Load an STL from a ZIP file. Graphic operations for rotating, panning and zooming. View your model in orthogonal or perspective mode. Obtain info on the model: triangle count, bounding box, area, and volume. Set up rendering options, faces, edges, points, and transparency. Render using a clipping plane (useful for viewing interiors). App now remembers each file graphic setting. Added buttons for graphic operations.

Online 3D Viewer is a free and open-source web solution to visualize and explore 3D models right in your browser. This repository contains the source code of the website and the library behind it. The website supports several file formats for import and export. If a file format has text and a binary version, usually it's recommended to use the binary version. There are several ways to load models. You can use files from your computer or load files hosted on an external web server. You can load models from your computer. In this case, the model won't be uploaded to any web server, the entire process happens in your browser. You can load models by URL with the open URL button on the toolbar. Sometimes you see missing files in the tree. It means that your model refers to another file, but they are not selected to import. To solve the issue you have to import the model again together with the referenced files, or just import the missing files on their own.