OPC UA .NET Standard Stack

🆕 This is version 2.0 of the OPC UA .NET Standard Stack (current master).

Looking for the supported 1.x release? It lives on the master378 branch (last release: 1.5.378). All new feature work happens here on master; master378 continues to receive security and critical-bug fixes for the 1.x line.

The official OPC Foundation reference implementation of OPC UA for .NET — a cross-platform stack with client, server, PubSub, GDS, complex types, and source-generated tooling. Used in production across industrial control, manufacturing, energy, and IoT systems.

📦 What it is

• A full-stack OPC UA implementation — Core / Client / Server / PubSub / GDS / LDS / Complex Types / Device Integration / Positioning libraries built on .NET, with UA-TCP and HTTPS transports.
• Cross-platform — runs on .NET 10, .NET 9, .NET 8 (LTS), .NET Framework 4.8; ships Native-AOT-friendly assemblies.
• Conformance regression testing — the reference server is tested with the Compliance Test Tool (CTT) through the CTT regression workflow. These results identify regressions; they do not constitute product certification.
• Companion-spec coverage — Part 9 (Alarms & Conditions), Part 10 (Programs), Part 11 (Historical Access), Part 13 (Aggregates), Part 16 (State Machines), Part 17 (Alias Names), Part 18 (Role Management), Part 20 (File Transfer), Part 100 (Device Integration), Part 110 (Asset Management Basics), Parts 210/211 (Relative Spatial Location and Global Positioning), OPC-10030 (ISA-95 Common Model) with OPC-10031-4 Job Control V1/V2, OPC 30270 / OPC UA for Asset Administration Shell V2 and V3, OPC 10100-1 (WoT Connectivity), Part 200 (Industrial Automation), OPC 40001-1/-2/-3/-4/-101 (Machinery with Process Values, Job Management, Energy and Result Transfer), OPC 34100 (Energy Consumption Management), OPC 30081 (PA-DIM), OPC 40010-1 (Robotics), OPC 40100-1/-2 (Machine Vision control and asset management), OPC 40501-1 and OPC 40505 (Machine Tools and independent wireless peripherals), OPC 40210 (Geometric Measurement Systems, with its documented upstream Production-facet exception), OPC 40020-1 (Cranes and Hoists), OPC 40223 (Pumps and Vacuum Pumps), OPC 30010 (AutoID Devices), OPC 40200 (Weighing Technology) with OPC 30050 (PackML).
• Hosting and code generation — Microsoft.Extensions.DependencyInjection hosting (services.AddOpcUa()), fluent server + client builders, source-generated NodeManagers and DataTypes, and an MCP server so LLMs / Copilot can drive an OPC UA client.

For the full feature breakdown see OPC UA Profiles and Facets and the What's New in 2.0 tour.

🚀 Getting started

To run a first OPC UA client and server, from NuGet packages or from the samples in this repository, follow Getting started. The documentation index then leads from the core concepts to advanced and experimental features.

The recycling operator console demonstrates live browser monitoring, native companion-specification inspection, material genealogy, and authorized controls over the synthetic recycling line.

You need a stable .NET SDK version 10.0.400 or later to build the repo. global.json selects the highest installed stable SDK, including newer major versions. From the repository root:

dotnet restore UA.slnx
dotnet build UA.slnx

For the supported target frameworks and platform notes see the Developer Guide. The official NuGet packages are published to nuget.org under the OPCFoundation.NetStandard prefix — the meta package OPCFoundation.NetStandard.Opc.Ua bundles a default set of stack packages; see its package inventory. Reference PubSub and other optional feature packages separately, or select individual packages directly, e.g. OPCFoundation.NetStandard.Opc.Ua.Client for clients or OPCFoundation.NetStandard.Opc.Ua.Server for servers. Preview builds from every successful master build are available from the GitHub Packages NuGet feed, which is the only feed they are published to. nuget.org receives a version only through a manually approved promotion from a release/<major>.<minor> branch — that is where the 2.0.0-preview.N packages already on nuget.org came from, via the earlier release/2.0.0 line. To use those, enable prerelease packages and float with 2.0.0-preview.* until 2.0.0 is released. The XRegistry, WoT Connectivity, Robotics, CranesHoists, Redundancy, Positioning, OpenUSD, and AI package families, the Vision.OpenUsd renderer, and the Robotics MCP extension remain preview packages when the root version is promoted to a stable version, and keep their own -preview.N versions on nuget.org. This includes all CranesHoists model/server/client/MCP packages and their Debug variants. The Vision, MachineVision, MachineTool (including WMTP), and GMS model/client/server packages and their MCP packages follow the root version without a preview-only override; development builds still inherit the root prerelease version. See docs/ReleaseProcess.md for how and when stable versions are released.

Samples

The platform-independent sample applications show how to use the stack's core services and companion models in client/server workflows. More applications, including platform-specific examples, are available in the companion OPC UA .NET Samples repository.

Developer tools

• OPC UA MCP Server — installable .NET tool and container exposing OPC UA client operations to LLMs and Copilot. Embeddable libraries provide Part 4 services, PubSub, diagnostics, Robotics and Vision, plus industrial companion profiles for AMB, Machinery, Scales, Pumps, AutoID, Device Integration, ISA-95 and Positioning. The WoT and xRegistry profiles add asset/registry management and bounded document validation, planning and NodeSet conversion. Stack workflow profiles provide GDS/credential issuance, roles/users, files, alarms, history, schemas, and host-authorized PubSub and live WoT execution.

🔧 Migrating from 1.5.378 to 2.0

The 2.0 release introduces breaking API changes, and comes with a full prescriptive migration guide that links to per-area documentation for the migration sub-topics.

Most of the mechanical migration work is automated:

• OPCFoundation.NetStandard.Opc.Ua.MigrationAnalyzer NuGet — install it in your project to get 26 analyzer rules through UA0030 (excluding UA0013, UA0016, UA0017, and the shim-only UA0029) plus one-click code fixes for the patterns in the guide. Setup steps are in the package's NugetREADME.md.
• Migration agent skill — the opcua-v20-migration skill walks Copilot / Claude / any coding agent through installing the NuGet, running dotnet format analyzers to apply auto-fixes, and handling the remaining manual changes. It selects the migration sub-document for each symptom.

Copilot CLI discovers the skill automatically inside a clone. To install it for use in any repository:

copilot plugin marketplace add OPCFoundation/UA-.NETStandard
copilot plugin install opcua-v20-migration@opcua-dotnet

If you are still on 1.x and not ready to upgrade, stay on the master378 branch — it continues to receive security and critical-bug fixes.

🤝 Contributing and license

Community contributions are welcome. Fork the repository, make your changes on a branch, and open a pull request; see CONTRIBUTING.md for the contribution workflow.

Contributors must sign the OPC Foundation Contributor License Agreement (CLA). The CLA "I AGREE" gate is presented automatically on your first PR.

The project is licensed under the OPC Foundation MIT License. Report security vulnerabilities via the process documented in SECURITY.md.

📚 Further reading

• Documentation index — every per-feature doc with a one-line description.
• What's New in 2.0 — narrative tour of the 1.5.378 → 2.0 changes grouped by theme and layer.
• OPC UA Profiles and Facets — facets / transports / security policies the stack implements.
• Migration Guide — prescriptive per-version migration reference (links to docs/migrate/2.0.x/).
• OPC UA Online Reference — the official OPC 10000 series specification index.
• Preview Nuget package feed — prerelease builds from every successful master build.