The Netscape Portable Runtime, or NSPR, is a cross-platform abstraction layer library for the C programming language.

[4] NSPR provides functions for working with files, directories, anonymous pipes and network sockets.

[3][4] NSPR provides API to perform the basic malloc, calloc, realloc and free functions.

Depending on the platform, the functions may be implemented almost entirely in the NSPR runtime or simply shims that call immediately into the host operating system's offerings.

[3][4] Support for linking (shared library loading and unloading) forms part of NSPR's feature set.