cxxtools contains an argument-parser, a base-64 encoder/decoder, a C++ interface to iconv, md5-stream for easy MD5 calculation, threading classes, socket classes, a dynamic exception-safe buffer, a wrapper for dlopen/dlsym, a pool template (e.g., for a connection pool in a multi-threaded application), query_params, and a class for easy parsing of CGI parameters (GET and POST) in a CGI program.

libc++ is another implementation of the C++ standard library.

CodeMirror is a code editor component for the web. It can be used in websites to implement a text input field with support for many editing features, and has a rich programming interface to allow further extension.

The purpose is to decouple projects from DateTimeImmutable instantiation so that things can be tested properly.

SLEPc is the Scalable Library for Eigenvalue Problem Computations.

libc++abi is another implementation of low level support for a standard C++ library.