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 certified, 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, and .NET Standard 2.1; ships Native-AOT-friendly assemblies.
• Certified for compliance — the reference server has been certified through an OPC Foundation Certification Test Lab and is continuously verified against the latest Compliance Test Tool (CTT).
• Companion-spec coverage — Part 9 (Alarms & Conditions), 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), 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), OPC 40001-1 (Industrial Automation), OPC 40010-1 (Robotics).
• Modern developer surface — first-class 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

You need the .NET 10 SDK to build the repo. 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 pulls in everything, or reference 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. Official public 2.0 preview releases are also on nuget.org. Enable prerelease packages and use 2.0.0-preview.* to float to the latest published 2.0.0-preview.N release.

Samples

The stack also includes a large collection of platform-independent sample applications that turn its core services and companion models into runnable 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 that exposes OPC UA client operations as MCP tools for LLMs and Copilot. The tools also ship as libraries (…Opc.Ua.Mcp.Core, .PubSub, .Diagnostics, .PubSub.Diagnostics) so an application can embed them next to its own MCP tools.

🔧 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 small residual manual patterns. The skill knows which sub-doc to load for each symptom so it stays context-efficient.

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.