GnuTLS (/ˈɡnuː ˌtiː ˌɛl ˈɛs/, the GNU Transport Layer Security Library) is a free software implementation of the TLS, SSL and DTLS protocols.

It offers an application programming interface (API) for applications to enable secure communication over the network transport layer, as well as interfaces to access X.509, PKCS #12, OpenPGP and other structures.

GnuTLS consists of a library that allows client applications to start secure sessions using the available protocols.

It also provides command-line tools, including an X.509 certificate manager, a test client and server, and random key and password generators.

[14] Soon afterward, developer Paolo Bonzini ended his maintainership of GNU Sed and Grep, expressing concerns similar to those of GnuTLS maintainer Mavrogiannopoulos.