OPC Unified Architecture (OPC UA) is a cross-platform, open-source, IEC62541 standard for data exchange from sensors to cloud applications developed by the OPC Foundation. Distinguishing characteristics are: The specification is freely available on the OPC Foundation website and is split into several parts to ease implementation, but only OPC UA stack vendors need to read them, end users simply leverage existing commercial and/or open-source stacks available in all popular programming languages Wikipedia