Reference
OPC UA SDKs and code
The open-source OPC UA stacks by language, with pinned versions, real constraints, and the same twelve tasks written out in each: connect, browse, read, write, subscribe, call a method, certificates, custom structs, history, alarms, PubSub and error handling.
Full recipe matrix 4
Python: asyncua (FreeOpcUa/opcua-asyncio)asyncua is the maintained Python OPC UA stack: asyncio-native, client and server, with a synchronous wrapper for scripts. It is the fastest way to getNode.js / TypeScript: node-opcuanode-opcua is a complete OPC UA implementation in TypeScript: client, server, discovery and aggregation. MIT-licensed, which makes it the easiest stacC# / .NET: OPCFoundation/UA-.NETStandardUA-.NETStandard is the official reference implementation, which makes it the definitive answer to "what should this do?" and the stack most likely to C: open62541open62541 is the stack for embedded and constrained targets: portable C99, a single-file amalgamation you can drop into a build, and an EventLoop plug
Stack guides 6
Java: eclipse-milo/miloEclipse Milo is the mainstream JVM OPC UA stack, client and server, targeting the 1.05 specification family. It is the obvious choice inside an existiGo: gopcua/opcuagopcua is a client-focused OPC UA implementation in pure Go, MIT-licensed. It suits a collector or gateway service in a Go estate, where a single statRust: locka99/opcuaA client and server OPC UA implementation in Rust under MPL-2.0. Attractive where memory safety without a garbage collector is the point: an edge colC++: open62541pp and vendor SDKsThere is no dominant open C++ OPC UA stack. In practice C++ projects either wrap open62541 with open62541pp for RAII and type safety, or buy a commercPython (legacy): FreeOpcUa/python-opcuaThis is the old Python stack, imported as `opcua`. It is deprecated and superseded by asyncua. It appears here only because a great deal of published MATLAB / LabVIEW: OPC Toolbox / OPC UA ToolkitBoth MATLAB and LabVIEW offer first-party OPC UA client add-ons. They matter because a lot of test-bench and R&D work lives in these environments, and
Last verified 7 September 2026 against OPC UA 1.05.07. OPC UA Connect is an educational resource and is not affiliated with the OPC Foundation.