OpenOpcUa is a complete OPC UA technology stack designed for industrial environments that require reliability, interoperability and long‑term maintainability. Originally created as an Open Source C/C++ project, OpenOpcUa has evolved over the years based on the needs of industrial users worldwide.
Since 2022, OpenOpcUa is no longer an Open Source project. At the request of its major industrial adopters, the open source licensing model was discontinued. OpenOpcUa is now distributed as freeware, while the source code remains accessible under a commercial licensing model for integrators, OEMs, ISVs and industrial partners.
A Technology Stack Used Worldwide
OpenOpcUa was initially designed to help developers build OPC UA Clients and Servers on Windows, Windows CE, Linux and VxWorks. Over time, it became a robust and unified codebase used in production systems across multiple industrial sectors.
Key architectural principles include:
- A single codebase for all supported platforms
- A ready‑to‑use OPC UA server
- Extensibility through Add‑ins
- A powerful API for building custom OPC UA clients
- Full support for existing and future OPC UA information models
- Dynamic loading of information models from UANodeSet XML files
OpenOpcUa is fully compliant with the OPC Foundation Compliance Test Tool (CTT), ensuring interoperability with major industrial systems.
Add‑ins Architecture
OpenOpcUaCoreServer can be extended using Add‑ins.
Two families of Add‑ins are supported:
VPI Add‑ins
Communication drivers such as Modbus, S7, Profibus, and other field protocols.
VFI Add‑ins
Interfaces for relational databases (RDBMS) or binary file‑based data sources.
This modular approach enables companies to integrate OpenOpcUa into existing architectures or legacy systems without modifying the core server.
A Robust OPC UA Information Model Engine
OpenOpcUa supports information models dynamically, without recompiling the server.
Models are loaded from UANodeSet files that conform to OPC Foundation specifications.
This allows integrators to deploy:
- Vendor‑specific information models
- Companion specifications
- Custom industrial models
- Complex hierarchical structures
- Data‑driven automation models
penOpcUa (OOUA) is no longer an Open Source project. At the request of its main industrial users, the Open Source model was discontinued in 2022. Since then, OpenOpcUa has been distributed as a freeware, while the source code remains accessible under a commercial licensing model. Originally created as an Open Source C/C++ codebase for OPC UA product development (under the CECILL‑C license with a no‑fork clause), OpenOpcUa enabled developers to easily build OPC UA clients and servers on Windows, Windows CE, Linux, and VxWorks.
Industrial Strength and Long‑Term Support
OpenOpcUa has been used for more than 15 years by industrial companies requiring stable and long‑term‑supported OPC UA implementations.
Its goals include:
- Providing a professional‑grade C/C++ codebase for OPC UA
- Accelerating the adoption of OPC UA in industrial systems
- Helping engineers understand and deploy the OPC UA architecture
- Offering a stable and maintainable solution for OEMs, integrators and automation vendors
OpenOpcUaCoreServer was the first Certified Open Source OPC UA Server recognized by the OPC Foundation before the licensing transition.
Collaboration Tools
OpenOpcUa provides collaboration interfaces and project tools that help teams integrate, test and deploy OPC UA‑based systems efficiently.
Documentation, examples, community resources and industrial feedback have contributed to shaping the technology into a reliable and production‑ready solution.
Today and the Future
OpenOpcUa continues to evolve in response to industrial IoT, Industry 4.0, interoperability and cybersecurity requirements.
The roadmap focuses on:
- Strengthening the core OPC UA stack
- Supporting advanced companion specifications
- Enhancing security and certificate management
- Optimizing performance for large‑scale deployments
- Extending Add‑in capabilities
- Supporting modern platforms and ecosystems
OpenOpcUa remains a strategic technological building block for industrial companies seeking a reliable and extensible OPC UA implementation.
FAQ – About OpenOpcUa
What is OpenOpcUa?
OpenOpcUa is a complete C/C++ OPC UA technology stack designed for industrial systems that require high reliability, interoperability and long‑term support. It provides a unified codebase for building OPC UA servers, clients and custom information models.
Is OpenOpcUa still an Open Source project?
No. OpenOpcUa was originally released as Open Source but this model was discontinued in 2022 at the request of major industrial users. The software is now distributed as freeware, and the source code is available through a commercial licensing model.
What platforms are supported by OpenOpcUa?
OpenOpcUa supports Windows, Windows CE, Linux and VxWorks. The same codebase runs across all these platforms, ensuring consistent behavior and simplified integration.
What are VPI and VFI Add‑ins?
VPI Add‑ins are communication drivers (e.g., Modbus, Profibus, S7).
VFI Add‑ins are interfaces for relational databases or binary file structures.
These Add‑ins extend the OpenOpcUaCoreServer without modifying its core.
Does OpenOpcUa support dynamic OPC UA information models?
Yes. OpenOpcUa loads OPC UA information models dynamically from UANodeSet XML files conforming to OPC Foundation standards. No recompilation is required.
Is OpenOpcUa compliant with OPC Foundation standards?
Yes. The codebase is compliant with the OPC Foundation Compliance Test Tool (CTT) to ensure high compatibility with other OPC UA products.
Who uses OpenOpcUa?
OpenOpcUa is used by industrial companies, OEMs, system integrators, automation vendors and research centers worldwide, especially in Industry 4.0 and IoT environments.
Can OpenOpcUa be customized?
Yes. Through Add‑ins, information models and the development API, OpenOpcUa can be adapted to specific industrial architectures, protocols and data models.