||This article needs additional citations for verification. (July 2010)
The Apache Portable Runtime (APR) is a supporting library for the Apache web server. It provides a set of APIs that map to the underlying operating system (OS). Where the OS doesn't support a particular function, APR will provide an emulation. Thus programmers can use the APR to make a program truly portable across platforms.
APR originally formed a part of Apache HTTP Server, but the Apache Software Foundation spun it off into a separate project. Other applications can use it to achieve platform independence.
The range of platform-independent functionality provided by APR includes:
Similar projects 
- GLib provides similar functionality. It supports many more data structures and OS-independent functions, but fewer IPC-related functions. (GLib lacks local and global locking and shared-memory management.)
- Netscape portable runtime (NSPR) is a cross-platform abstraction library used by the Mozilla project. It is used by another subproject of Mozilla application framework (XPFE) to provide cross-platform graphical user interface (GUI) functionality.
- Adaptive Communication Environment (ACE) is an object-oriented library written in C++ similar in functionality to APR. It is widely deployed in commercial products.
- commonc++ is a cross-platform C++ class library for systems programming, with much of the same functionality as APR.
- POCO is a modern C++ framework similar in concept but more extensive than APR.
- WxWidgets is an object-oriented cross-platform GUI library that also provides abstraction classes for database communication, IPC and networking functionality.
- Qt, a cross-platform application development framework with similar features, can also foster GUI development.
External links