- community-curated standard library and language reference
- C++98 - C++20 and technical specifications (TS)
- C89 - C17
- many (runnable) examples
Offline documentation browser for
- C++ and C docs from cppreference.com
- Boost, Qt4, Qt5, Qt6 docs
- Python docs
- … and many other languages, tools and libraries
The browser tree could be improved, unfortunately C++ entities are not properly categorized into concepts, types, etc.
Ivan Čukić wrote a nice script that allows fuzzy browsing of Zeal resources from the command line.