3 ms·4. It's not proprietary and doesn't restrict people's ability to freely use their web browser.by yarrel 12y ago4. It's not proprietary and doesn't restrict people's ability to freely use their web browser.teraflop 12y agoWhat do you mean by "proprietary"? Pdfium is BSD-licensed, and pdf.js uses the Apache 2 license; both are extremely permissive.async5 12y agoExcept one does not provide protection from the patents.