Botan is a BSD-licensed cryptographic library written in C++. It provides a wide variety of cryptographic algorithms, formats, and protocols, e.g. SSL and TLS. It is used in the Monotone distributed revision control program.
The project was originally called OpenCL, a name now used by Apple Inc. and Khronos Group for a heterogeneous system programming framework. It was renamed Botan in 2002.
In 2007, the German Federal Office for Information Security contracted FlexSecure GmbH to add an implementation of Card Verifiable Certificates for ePassports to Botan; the modified version of Botan was released under the name InSiTo.