The LANG API development environment provides a comprehensive library (DLL) for easily interfacing with LANG positioning controllers from the LSTEP express, LSTEP, ECO-STEP, and MCL series. The development environment includes a set of functions that allow users to easily take advantage of the controller’s full range of features without detailed knowledge of the command set. It also includes the necessary header files for integration with various programming languages. LANG API is compatible with Windows 11 (64-bit) and earlier operating systems. The documentation of the function calls is included in the package.