PubNub has introduced a new Posix C SDK designed for developers who need to write straight Posix C code, offering flexibility and control over memory allocation. This SDK is particularly useful for applications requiring maximum speed or operating on resource-constrained devices like low-end Linux systems or embedded ARM chips. It allows developers to choose between a "sync" interface for ease of use and a "callback" interface for greater flexibility, and supports optional SSL/TLS compilation. Additionally, special versions of the SDK are available for Windows C, Windows C++, and Posix C++, with C++ SDKs providing efficient abstractions with minimal overhead. While not suitable for Atmel-based Arduino systems, for which the PubNub Arduino Library is recommended, this C SDK is tailored for scenarios where developers need direct, low-level coding capabilities.