Weiqi,
As Nick said you can build a local copy of the HTML version of the API documentation (that is, the documentation of all the functions in Cantera) using Sphinx and Doxygen. When you build Cantera, you can follow Nick's suggestion, or use
scons build sphinx_docs=y doxygen_docs=y
to build both at once. The dependencies required to build the docs are
on the website.
If you then want a PDF copy of the docs, you can build that as well. Once the library is built, change to the doc directory and use the sphinx-build command (installed with Sphinx) to build LaTeX sources, which can be compiled using pdflatex
scons build ...
cd doc/
sphinx-build -b latex . _build
cd _build
make
should make a PDF of the API docs.
If you have specific suggestions for how to improve the new website, please feel free to share, either here or you can email me directly! I'm not sure what you found better about the old website, and I would be very interested to hear what you think; personally, I found it impossible to read and figure out where I wanted to go, and I hope the new site is an improvement in that regard. The API documentation is still split out by category, so we tried to maintain that portion at least.
Thanks,
Bryan