About StepPDF 3D
Licenses and attributions
StepPDF 3D is built on third-party open-source components. This page lists the components shipped with the site, what they are used for, their license, and where to find the full license texts and the original source code.
Components shipped with the site
| Component | Version | Use on the site | License | License text | Source code |
|---|---|---|---|---|---|
| Open CASCADE Technology (OCCT) | Bundled inside occt-import-js | CAD kernel that reads STEP, IGES and BREP (compiled to WebAssembly). | LGPL-2.1 with the Open Cascade additional exception | LGPL-2.1 text Open Cascade exception | Repository Exact source code (7.6.1, d2abb6d) |
| occt-import-js | 0.0.23 | WebAssembly bridge between the browser and OCCT. | LGPL-2.1 | LGPL-2.1 text | Repository Exact source code (0.0.23) Notes and modifications |
| three.js | r185 (0.185.1) | 3D viewer, camera controls, STL/OBJ/3MF/PLY/glTF/VRML loaders and STL/OBJ/GLB exporters. | MIT | MIT license | Repository |
| fflate | 0.8.2 (bundled with three.js) | Compression and decompression (PRC, 3MF, PDF). | MIT | MIT license | Repository |
| Chevrotain | 9.0.1 (bundled with three.js) | Parser used by the VRML loader. | Apache-2.0 | Apache 2.0 license | Repository |
| pdf-lib | Version shipped on the site (the file does not state a version number) | Building the 3D PDF and reading PDFs in the viewer. | MIT | MIT license | Repository |
| pako (inside pdf-lib) | — | zlib compression used by pdf-lib. | MIT (the part ported from zlib is under the Zlib license) | MIT license | Repository |
| tslib (inside pdf-lib) | — | TypeScript helper functions bundled in pdf-lib. | Apache-2.0 (notice kept at the top of the file) | Apache 2.0 license | Repository |
| StepPDF 3D PRC writer and reader | Based on Asymptote 2.86 | Files /js/core/prc-writer.js, /js/core/prc-double-table.js and /js/core/prc-reader.js: a JavaScript port of the Asymptote PRC writer (oPRCFile, PRCbitStream and PRCdouble, by Orest Shardt and Michail Vidiassov), with reading based on PRCTools. | LGPL-3.0 or later (license of the original code) | LGPL-3.0 text GPL-3.0 text | Repository |
Notes
- The site’s own JavaScript files are served unminified, so their code can be read directly at the paths shown.
- Copyright notices included in third-party files are kept as they come.
- The typefaces (Archivo and IBM Plex) are loaded from Google Fonts and are not distributed from this site.
- Adobe, Acrobat and Reader are trademarks of Adobe. Other program and format names belong to their respective owners.
- If you spot an error in this information, write to us from the contact page.
Last reviewed: October 24, 2026.