GnuTLS is a secure communications library implementing the SSL, TLS, and DTLS protocols and technologies around them. It provides a simple C language application programming interface (API) to access the secure communications protocols, as well as APIs to parse and write X.509, PKCS #12, OpenPGP, and other required structures. It is intended to be portable and efficient with a focus on security and interoperability.
GTK, which stands for the Gimp ToolKit, is a library for creating graphical user interfaces. It is designed to be small and efficient, but still flexible enough to allow the programmer freedom in the interfaces created. GTK provides some unique features over standard widget libraries.
libdvdcss is a cross-platform library for transparent DVD device access with on-the-fly CSS decryption. It currently runs under Linux, FreeBSD, NetBSD, OpenBSD, BSD/OS, Solaris, BeOS, Win95/Win98, Win2k/WinXP, MacOS X, HP-UX, QNX, and OS/2. It is used by libdvdread and most DVD players such as VLC because of its portability and because, unlike similar libraries, it does not require your DVD drive to be region locked.
GNU libmicrohttpd is a small C library for embedding HTTP server functionality into other applications. It is reentrant, fast, supports HTTP 1.1, and permits listening on multiple ports. The API is simple and still powerful enough to allow programmers to use the entire HTTP feature set. SSL/TLS support is available as an option.
zlib is designed to be a free, general-purpose, legally unencumbered, lossless data-compression library for use on virtually any computer hardware and operating system. The zlib data format is itself portable across platforms. Unlike the LZW compression method used in Unix compress(1), the compression method currently used in zlib essentially never expands the data. (LZW can double or triple the file size in extreme cases.) zlib's memory footprint is also independent of the input data and can be reduced, if necessary, at some cost in compression.
CUPS is a standards-based printing system for Mac OS X and other Unix-like operating systems. It provides the System V and Berkeley command line interfaces, and uses the Internet Printing Protocol ("IPP") as the basis for managing print jobs and queues. The Line Printer Daemon (LPD) Server Message Block (SMB), and AppSocket (a.k.a. JetDirect) protocols are also supported with reduced functionality. CUPS adds network printer browsing and PostScript Printer Description ("PPD") based printing options to support real world printing.
Embedthis Appweb is a fast, little embedded Web server. It is unmatched in efficiency and serves pages at native speed, using an event-driven, non-blocking core to serve multiple requests using minimal resources. It has integrated caching and the Embedded Server Pages C-Language Web framework. Without compromising performance, it has extensive security controls and a rigorous security sandbox that helps protect the server and mitigate denial-of-service attacks. It is one of the most widely deployed embedded Web servers and is used in networking equipment, telephony, mobile devices, industrial control, and consumer and office equipment, and in high-performance Web services.
curl and libcurl is a tool for transferring files using URL syntax. It supports HTTP, HTTPS, FTP, FTPS, SCP, SFTP, TFTP, DICT, TELNET, LDAP, POP3, IMAP, SMTP, RTSP, RTMP, and FILE, as well as HTTP-post, HTTP-put, cookies, FTP upload, resumed transfers, passwords, port numbers, SSL certificates, Kerberos, and proxies. It is powered by libcurl, the client-side URL transfer library. There are bindings to libcurl for about 40 languages and environments.