Licenses
Some of the code this site sends to your browser was written by other people. Here is what it is and where the original lives.
pdf.js (renders PDFs in the browser)
Apache 2.0, by Mozilla. We ship it unmodified. It is what lets us open your PDF without uploading it.
fflate (compression)
MIT. It compresses the black and white images inside the PDF we build.
Our own code
The fax geometry, the cover sheet drawing and the PDF and TIFF writers are ours. What goes into each file is spelled out in the source.