BearSSL is an implementation of the SSL/TLS protocol (RFC 5246) written in C. It aims at offering the following features: - Be correct and secure. In particular, insecure protocol versions and choices of algorithms are not supported, by design; cryptographic algorithm implementations are constant-time by default. - Be small, both in RAM and code footprint. For instance, a minimal server implementation may fit in about 20 kilobytes of compiled code and 25 kilobytes of RAM. - Be highly portable. BearSSL targets not only "big" operating systems like Linux and Windows, but also small embedded systems and even special contexts like bootstrap code. - Be feature-rich and extensible. SSL/TLS has many defined cipher suites and extensions; BearSSL should implement most of them, and allow extra algorithm implementations to be added afterwards, possibly from third parties.