It's an extension of pdf.js, not a fork.

The parent didn't ask if it was a fork or not.

The point being that this is an extension, and contributing back to that dependency is orthogonal.

If they contribute back was the question.

Our intention with PDF.js Express is to provide a solution that meets a market need for a PDF.js viewer with out-of-the-box features. Building this viewer that wraps around the PDF.js engine was no small task and we do hope that it will provide some value to developers. With that said, our goal is to grow usage of PDF.js Express and the PDF.js project. Ultimately the more developers we can bring to the platform the better it is for us and for the open-source community. We’ve started by creating articles that should help others get started with vanilla pdf.js: How to Build a PDF.js Viewer in React + Typescript [1] and How to Add Zoom Controls to a PDF.js Viewer [2]. We plan on creating more of these guides and now that we've launched this product, we will be looking to help move the pdf.js project forward.

[1] https://pdfjs.express/blog/building-pdfjs-viewer [2] https://pdfjs.express/blog/build-pdfjs-viewer-ui

So you plan to post some advertising tutorials and grow the developer community, aka you're doing nothing, but you're not contributing to the project that is in the core of your product? No wonder open source projects die, no one gives back.

I'm not here to argue, just making an observation.