The PS/SC Workgroup specification defines what a compliant API for smart card access must look like. The existing compliant implementations are winscard on Windows (which is the de facto canonical implementation of PC/SC) and PCSClite, a free-software implementation providing an API compatible with winscard.h. The CCID project provides PCSClite with free software smart card and card reader drivers.
PC/SC support in platforms is as follows:
- Microsoft Windows: ships with winscard (out of the box).
- macOS: ships with a forked version of PCSClite (out of the box).
- Linux: PCSClite can be installed.
- ChromeOS: Available via the Smart Card Connector extension, which bundles PCSClite and CCID compiled to PNaCl/WebAssembly.
Even though the existing PC/SC implementations share pretty much the same C API, meaning that a C application (when properly written) can be compiled against both winscard (on Windows) and PCSClite (on macOS and Linux) with little to no modifications, their actual behaviors differ significantly (some examples). Such differences cannot be ignored or be transparent to users of a Web API that is at the same abstraction level, providing the same concepts and features, as that C PC/SC API.