What Is NX Open? The NX Open API for Siemens NX Explained

Siemens NX Open and the Future of Industrial Engineering Automation

Architecture of Programmable CAD/CAM/CAE, Model-Based Definition, AI-Driven Workflows, and the Expanding NX Ecosystem

NX Open is the official programming interface of Siemens NX. It lets engineering teams automate most of what they do interactively in NX, from features, assemblies and drawings to PMI, attributes and batch jobs, in C#, Visual Basic, C++, Java or Python. Small tasks start as recorded journals; larger tools become compiled, signed applications with their own dialogs. This guide covers the architecture, the use cases, MBD and the AI layer on top of NX Open.

The European and global manufacturing sector is experiencing an unprecedented convergence of advanced computer-aided engineering, artificial intelligence, and cloud-connected product lifecycle management. At the epicenter of this transformation stands Siemens NX — widely recognized by analysts such as Frost & Sullivan as the clear innovation leader in mechanical computer-aided design for 2025 [1]. No longer merely a design tool, NX has evolved into a comprehensive, multidisciplinary platform spanning mechanical and electrical design, simulation, manufacturing, and now immersive engineering through augmented and virtual reality.

This technical whitepaper provides an in-depth exploration of Siemens NX Open — the official Application Programming Interface (API) that enables engineers and developers to automate, customize, and extend every facet of the NX environment. We examine the expanding ecosystem of over 140 NX add-on modules, the strategic advantages of Model-Based Definition (MBD) in modern manufacturing, the integration of AI-powered copilots and intelligent design workflows, and the role of NX within the broader digital twin and Teamcenter PLM ecosystem.

1. Understanding Siemens NX: The Complete Product Engineering Platform

1.1 From Unigraphics to Designcenter NX: A Legacy of Innovation

Siemens NX traces its lineage back to the original Unigraphics system, with data compatibility extending to approximately 1984. Today, rebranded under the Designcenter suite, NX delivers integrated CAD, CAM, CAE, additive manufacturing, and more within a single environment. The platform supports every aspect of product development — from initial concept sketches through detailed engineering, manufacturing programming, and quality inspection.

The NX Continuous Release process ensures that new features and add-on modules are delivered every six months, reducing the gap between innovation and deployment. This approach allows organizations to access the latest capabilities without the disruption and cost of traditional major version upgrades. The December 2025 release, for example, introduced significant advancements in AI-enabled design, real-time multi-user authoring, and model-based characteristics that reshape how engineering teams approach collaborative product development [2].

1.2 NX X: Cloud-Connected Engineering

With the introduction of NX X, Siemens brings the full power of NX to a cloud-managed, Software-as-a-Service (SaaS) model. NX X is locally installed but managed through the cloud, with automatic updates, configuration management, and license administration handled seamlessly. The platform offers four scalable tiers — Essentials, Standard, Advanced, and Premium — each targeting specific product development disciplines. NX X features full interoperability and data sharing across the Siemens Xcelerator portfolio, including NX CAM modules, Teamcenter, Simcenter, and other solutions, enabling organizations to connect comprehensive digital twins across an integrated digital thread [3].

The flexible Value Based Licensing model allows teams to access over 140 add-on modules from a shared token pool, checking modules in and out on demand without the need for individual purchases. New add-on modules are added to the token pool with each release at no additional cost, making the investment inherently future-proof.

2. NX Open: The Architecture of Programmable Engineering

2.1 What is NX Open?

NX Open is the official Application Programming Interface (API) provided by Siemens for the NX platform. It is a comprehensive framework that gives engineers and developers direct, programmatic access to the core capabilities of NX — enabling the creation of custom applications, automation of repetitive tasks, enforcement of design standards, and deep integration with enterprise systems such as PLM, ERP, and MES platforms [4].

Unlike simple macro recorders or limited scripting interfaces found in other CAD systems, NX Open is a full-featured API that mirrors the breadth and depth of NX’s interactive capabilities. Any operation that can be performed interactively within NX can be accessed and controlled programmatically through NX Open. This includes geometry creation and manipulation, feature-based modeling, assembly management, drafting and annotation, CAM programming, simulation setup, and much more.

2.2 Supported Programming Languages and Development Environments

One of NX Open’s greatest strengths is its language flexibility. The API supports multiple programming languages through a Common API architecture, ensuring identical automation capabilities regardless of which language a developer chooses:

C# (.NET): Currently the most widely adopted language for NX Open development in enterprise environments. C# combines strong typing, modern language features, and excellent integration with the .NET framework, making it ideal for building robust, maintainable automation solutions and custom add-ins.

VB.NET: Historically the preferred language for NX Open development and still widely used. VB.NET runs on the same .NET platform and NX Open API as C#, and many legacy automation scripts and applications are written in this language.

Python: Rapidly growing in popularity, especially among mechanical engineers who may not have deep programming backgrounds. Python’s readable syntax and extensive library ecosystem make it particularly attractive for journaling, scripting, and rapid prototyping of automation ideas. The integration with Visual Studio Code and PyCharm provides a modern development experience.

C/C++: Offers the highest performance and lowest-level access to NX internals. C++ is typically chosen for computationally intensive applications, complex geometric algorithms, or situations where maximum execution speed is critical.

Java: Provides cross-platform compatibility and is used in environments where Java infrastructure is already established, particularly in some aerospace and defense organizations.

2.3 The Journaling Capability: Rapid Automation Gateway

The NX Journal capability serves as the entry point for most NX Open automation initiatives. Journaling records interactive NX sessions and produces scripted files in Python, C#, Visual Basic, C++ or Java that can be edited, enhanced, and replayed at a later time. This approach dramatically lowers the barrier to automation — an engineer can simply perform a task interactively, review the generated journal code, and then modify it to create a parameterized, reusable automation script.

Journals are particularly powerful for tasks such as changing body or face colors across multiple components, moving objects to specific layers, managing attributes, batch processing files, generating standardized drawing sheets, and performing repetitive geometry modifications. The journal capability transforms the question from “Can I automate this?” to “How quickly can I automate this?” [5].

2.4 Block UI Styler: Building Professional User Interfaces

For more sophisticated automation solutions, NX Open includes the Block UI Styler — a tool for creating custom dialog boxes and user interfaces that integrate seamlessly into the NX environment. Developers can build intuitive, professional-looking dialogs that guide users through well-defined workflows, collect input parameters, validate data, and trigger complex automation sequences.

The Block UI Styler enables organizations to create applications that feel native to NX, reducing training time and ensuring that even complex automated workflows can be operated by engineers who are not programmers. Combined with the NX ribbon bar customization capabilities, custom applications can be deployed alongside standard NX tools, making them immediately accessible to the entire engineering team.

2.5 Knowledge Fusion: Rule-Based Engineering

Beyond traditional API programming, NX offers Knowledge Fusion — an engineering knowledge management system that allows organizations to capture and embed design rules, engineering formulas, and manufacturing constraints directly within the CAD environment. Knowledge Fusion rules can drive parametric geometry, enforce design standards, and automatically adapt designs based on changing requirements.

The ability to execute Knowledge Fusion applications is included with all NX Mach Series solutions as a runtime license, while the Knowledge Fusion Author programming capability is available as an add-on module. This two-tier approach allows organizations to widely deploy rule-based designs while limiting authoring to trained specialists [6].

3. Practical Applications of NX Open Automation

3.1 Industry-Specific Use Cases

The breadth of NX Open’s capabilities translates into automation opportunities across virtually every manufacturing sector:

Automotive Engineering: Standard part generation can be automated to create families of design variants from parameterized templates. Integration between NX and PLM systems ensures seamless data management as variants proliferate. BOM generation, design rule checking, and variant configuration are common automation targets.

Aerospace and Defense: Stringent compliance requirements make rule-based modeling particularly valuable. NX Open enables automated stress report generation, enforcement of customer-specific design standards such as those required by military specifications, and traceability of design decisions through integration with Teamcenter.

Manufacturing and Tooling: Custom part libraries, automated cost estimation tools, and validation plugins streamline production workflows. NX Open can automate the generation of CNC programs through NX CAM integration, potentially reducing programming time by up to 90% when combined with feature-based machining capabilities [7].

Heavy Machinery and Industrial Equipment: Complex assemblies with thousands of components benefit enormously from automation. NX Open can generate simulation-ready models, create motion and kinematics tools for advanced mechanical systems, and automate the configuration of large assemblies based on customer specifications.

3.2 The Business Case for NX Open Automation

The return on investment from NX Open automation extends far beyond simple time savings. Organizations that systematically deploy automation typically realize benefits across multiple dimensions:

Knowledge Preservation: By encoding engineering best practices, tribal knowledge, and lessons learned into automated workflows, organizations protect against knowledge loss due to employee turnover, retirement, or organizational restructuring. The automation itself becomes a form of institutional memory.
Process Standardization: Automated workflows enforce consistent processes across teams, sites, and geographies. This is particularly valuable for organizations operating under quality management systems such as ISO 9001, AS9100, or IATF 16949.
Error Reduction: Human error in repetitive tasks is inevitable. Automation eliminates entire categories of errors — incorrect dimension entries, missed tolerance callouts, wrong material specifications, inconsistent naming conventions — that would otherwise propagate through the design-to-manufacturing chain.
Resource Reallocation: When engineers spend less time on repetitive, low-value tasks, they can devote more attention to innovation, problem-solving, and complex design challenges.
Scalability: Automated processes scale linearly with volume. Whether an organization needs to process 10 or 10,000 parts, the automation runs with the same consistency and speed [8].

3.3 Integration with Enterprise Systems

NX Open’s capabilities extend beyond the CAD environment to enable deep integration with enterprise-level systems:

PLM Integration (Teamcenter): NX Open can interact with Teamcenter to automate workflows such as check-in/check-out, revision management, workflow routing, and metadata population. This integration ensures that design automation respects the organization’s data management policies and change management processes.

ERP Integration: Custom NX Open applications can query ERP systems for material availability, cost data, or supplier information, and feed this data directly into the design process. Conversely, design data such as BOMs, material specifications, and manufacturing requirements can be pushed to ERP systems automatically.

MES Integration: Manufacturing Execution Systems can receive toolpath data, setup sheets, and manufacturing instructions generated through NX Open automation, closing the loop between engineering design and shop floor execution.

4. The NX Add-On Ecosystem: Extending Platform Capabilities

4.1 Over 140 Modules and Growing

The NX platform’s extensibility goes far beyond what is possible through NX Open programming alone. Siemens offers over 140 add-on modules that extend NX’s capabilities into specialized domains. These modules are developed by Siemens and, in many cases, by certified third-party partners, and they are delivered through the Value Based Licensing token system that allows flexible, on-demand access [9].

The add-on ecosystem spans categories including advanced simulation tools, specialized design applications for industries such as marine engineering and architecture, direct translators for competitive CAD formats (CATIA V4/V5, Creo, SolidWorks, Inventor, and others), programming and customization toolkits, standard parts applications, and additive manufacturing tools.

4.2 Key Categories of NX Add-On Modules

Design and Modeling Add-Ons: Modules such as NX Realize Shape for subdivision surface modeling, NX Mold Wizard for automated mold design, and NX Molded Part Designer for creating features like snap fits and grooves extend the core design capabilities into specialized manufacturing domains. The December 2025 release introduced intelligent standard parts in NX Mold Wizard that update in real-time with configuration changes [10].

Simulation and Analysis: NX Performance Predictor enables designers to simulate mechanical behavior directly within NX, with recent enhancements supporting assembly-level simulation. NX CFD Designer, introduced in the June 2025 release, brings fluid flow and thermal simulation capabilities directly into the NX CAD workspace for the first time, powered by Simcenter FLOEFD technology [11].

Manufacturing and CAM: NX CAM modules provide comprehensive, integrated NC programming for milling, turning, and wire EDM. Advanced feature-based machining automates the creation of optimized machine programs directly from design models.

Immersive Engineering: NX Immersive Designer, developed in collaboration with Sony, enables engineers to create, view, and edit 3D CAD designs in virtual reality or augmented reality using a purpose-built head-mounted display with dual 4K OLED micro-displays. NX Immersive Collaborator extends this capability to multi-user collaborative sessions directly from the NX interface [12].

Quality and Inspection: NX Inspector represents a groundbreaking addition to the ecosystem, enabling the definition of model-based characteristics directly within the CAD workspace. This industry-first capability implements the Digital Metrology Standards Consortium’s standard for model-based characteristics, bridging design and downstream quality processes [13].

4.3 Third-Party Add-Ons and the Partner Ecosystem

Beyond Siemens’ own modules, a thriving ecosystem of third-party add-ons extends NX’s capabilities further. Notable examples include:

GWJ Technology Integration: Enables complex gear dimensioning using eAssistant software, with direct import into NX as fully parametric solid models.
CADENAS Integration: Provides access to extensive libraries of manufacturer-certified standard parts and supplier catalogs directly within NX.

5. Model-Based Definition (MBD): Transforming the Engineering Documentation Paradigm

5.1 The Shift from 2D Drawings to 3D-Centric Documentation

Model-Based Definition represents a fundamental shift in how products are defined, documented, and communicated across the manufacturing enterprise. Rather than relying on traditional 2D technical drawings as the authoritative source of product definition, MBD embeds all necessary manufacturing information — dimensions, tolerances, surface finishes, annotations, material specifications, and metadata — directly within the 3D CAD model [15].

This approach creates a single source of truth for product design, manufacturing, assembly, inspection, and all other downstream activities. The 3D model with its embedded Product Manufacturing Information (PMI) replaces the need for separate, redundant 2D drawings, fundamentally eliminating the synchronization problem that has plagued engineering departments for decades.

5.2 NX PMI and NX MBD: A Best-in-Class Solution

Siemens NX delivers what is widely regarded as the most mature and comprehensive MBD solution in the industry. The MBD portfolio consists of two complementary components:

NX PMI (Product Manufacturing Information): The foundational technology for model-based definition. NX PMI enables engineers to specify parts and assemblies directly in the 3D model, covering geometric design, surface finish, and the shape and position of design features. Faces and edges of the model are directly connected to PMI objects through associative links, ensuring that changes to geometry automatically propagate to annotations.

NX MBD (Model-Based Definition): Builds on NX PMI to provide advanced automation, validation, and management capabilities. The MBD Logic Editor provides an interactive diagramming interface for defining rules that automate PMI creation — for example, automatically generating complete hole callouts with diameter, threading, and tolerance specifications based on feature recognition. These rules are managed in the NX Reuse Library and can be deployed across the organization to ensure standardization.

The PMI Advisor, fully integrated within NX, provides real-time validation and notification to verify that PMI is compliant with industry standards such as ASME Y14.5, ISO GPS, and company-specific requirements. This immediate feedback prevents errors from propagating through the design process and ensures that the digital product definition is manufacturing-ready from the outset.

5.3 Convert to PMI: Bridging Legacy and Modern Workflows

Organizations with significant investments in traditional 2D drawings face a practical challenge: how to transition to MBD without discarding years of existing documentation. NX addresses this challenge with the Convert to PMI capability, which automatically converts drawing views and objects to corresponding model views and PMI objects. Engineers can convert entire drawings, selected sheets, specific views, or individual dimensions, providing granular control over the migration process [17].

This capability significantly reduces the cost and time required to adopt MBD, allowing organizations to progressively transition their existing product libraries while immediately applying MBD to new designs.

5.4 NX Inspector: Extending MBD into Quality and Manufacturing

Introduced in the 2025 updates, NX Inspector represents a groundbreaking advancement in model-based definition. It is the first CAD-native implementation of the Digital Metrology Standards Consortium’s standard for model-based characteristics, integrating data that engineers previously managed across a variety of separate documents and software tools.

NX Inspector allows designers to define and manage PMI characteristics directly within the NX CAD workspace, with each individual PMI object generating multiple quality and manufacturing requirements. For example, a single hole callout may contain characteristics defining its diameter, threading, and tolerance requirements. Integration with Teamcenter Quality ensures complete traceability across the digital thread, bridging design and production through a seamless data flow [18].

5.5 Strategic Advantages of MBD in Modern Manufacturing

The transition to model-based definition delivers measurable advantages across the product lifecycle:

Reduced Documentation Time and Cost: Eliminating the creation and maintenance of separate 2D drawings reduces the engineering documentation burden. Changes to product design require updating only the 3D model, rather than propagating modifications across multiple drawing sheets.
Improved Communication Accuracy: A single, authoritative 3D model eliminates the risk of discrepancies between 2D drawings and 3D geometry — a common source of manufacturing errors that can be extremely costly to correct downstream.
Automated Downstream Processes: PMI data is directly consumable by CAM systems for toolpath programming and by CMM systems for inspection programming. This eliminates manual reinterpretation of drawing information and enables end-to-end automation of the manufacturing chain.
Enhanced Collaboration: 3D models with embedded PMI can be published as Technical Data Packages in 3D PDF or JT format, providing interactive 3D visualization to non-CAD users across the supply chain.
Foundation for the Digital Twin: MBD is the enabler of the comprehensive digital twin. By completely capturing the product and all process information within the 3D model, MBD provides the foundational data layer upon which digital twin simulations, manufacturing execution, and lifecycle management are built [19].

6. Artificial Intelligence in Siemens NX: From Copilots to Predictive Design

6.1 The AI Imperative in Engineering Software

Artificial intelligence has emerged as the number-one technology investment area for manufacturers, with early adopters of AI technologies reporting time savings of more than 40% on common engineering tasks [20]. Siemens has approached AI in NX with a clear philosophy: augment engineering expertise rather than replace it. The AI capabilities built into Designcenter NX are designed to remove repetitive, low-value work and provide intelligent assistance, allowing engineers to focus on complex design challenges and innovation.

6.2 Designcenter X NX Copilot: Natural Language Engineering Assistance

The Designcenter X NX Copilot, introduced with the 2025 updates and significantly enhanced in the December 2025 release, represents a new paradigm in engineering software interaction. This generative AI assistant provides a natural language interface that translates conversational queries into domain-specific commands, leveraging Siemens’ extensive documentation and industry best practices [21].

Engineers can ask questions in plain language — about the best approach for a particular modeling task, how to resolve an error, or which command to use for a specific workflow — and receive expert-level guidance backed by factual information drawn directly from Siemens’ technical resources. The Copilot reduces time and effort on complex tasks by streamlining workflows and making NX more accessible, particularly for new users seeking to unlock functionality they may not yet be familiar with.

Importantly, the NX Copilot goes beyond simple documentation search. It understands engineering context, can provide step-by-step guidance for multi-step workflows, and directs users to the appropriate NX commands and features. For experienced users, it serves as a rapid reference tool; for newcomers, it functions as an ever-available expert mentor.

6.3 NX CAM Copilot: AI-Driven Manufacturing Programming

Siemens is also developing an AI copilot specifically for NX CAM that generates machining strategies from part geometry. With a minimal number of interactions, the CAM Copilot produces multiple possible machining approaches for a given feature, allowing the programmer to select and fine-tune the most appropriate strategy. This capability is designed to serve as a knowledge capture tool, helping bridge the engineering skills gap while delivering significant time savings — estimated at 80% or more of the time typically spent on CAM programming [22].

Unlike generic machining solutions, the NX CAM Copilot is designed to learn from company-specific programming practices, ensuring that generated strategies align with an organization’s established processes, tooling preferences, and machine capabilities.

6.4 AI-Powered Design Automation Features

Beyond conversational copilots, Siemens has embedded AI into specific design workflows within NX:

Select Similar Faces/Edges: Uses AI to identify geometrically similar features across complex parts, enabling bulk edits that would otherwise require tedious manual selection. This capability is particularly valuable for parts with hundreds of similar features.
PMI Prediction: Leverages AI to suggest appropriate PMI annotations based on feature geometry and previously applied annotations, ensuring consistency and completeness of manufacturing information across parts.
Design for Manufacture (DFM) Advisor: Automates early manufacturability assessments by analyzing part geometry and identifying potential challenges across multiple manufacturing processes — including drilling, milling, assembly, and molding — and providing actionable feedback directly within the NX interface [23].

7. The Digital Twin and PLM Integration Ecosystem

7.1 NX and Teamcenter: The Connected Digital Thread

The integration between NX and Siemens Teamcenter PLM creates a unified environment that streamlines the entire product development process. Teamcenter serves as the single source of product and process knowledge, coordinating all phases of development, standardizing processes, and accelerating decision-making.

When NX operates in managed mode with Teamcenter, engineering teams benefit from centralized data management, automated version control, structured change management workflows, and cross-functional collaboration. The June 2025 release enhanced this integration with improvements to dependent content export, improved Change Management accessibility, and streamlined collaboration features [24].

7.2 Teamcenter X: Cloud-Based PLM

Teamcenter X, the SaaS PLM offering on Siemens Xcelerator, provides the same core capabilities as on-premise Teamcenter in a managed cloud service. Organizations can manage requirements, configurations, workflows, and lifecycle data with secure access for distributed teams. The recent Teamcenter Digital Reality Viewer integration with NVIDIA Omniverse enables photorealistic visualization of complex engineering data, allowing stakeholders to interact with digital twins of products in unprecedented fidelity [25].

7.3 The Comprehensive Digital Twin

NX CAD data seamlessly integrates with the broader Siemens Xcelerator portfolio — Teamcenter for PLM, Simcenter for simulation and testing, Insights Hub for Industrial IoT, and Opcenter for manufacturing execution. This integration creates a comprehensive digital twin that spans the entire product lifecycle, from initial concept through manufacturing, operation, and service.

The digital twin is not merely a 3D model; it is a living, evolving virtual representation that incorporates design data, simulation results, manufacturing information, operational parameters, and service history. Digital twins are central to Siemens’ vision for the future of industrial technology, with significant investments in advancing their fidelity and utility [26].

8. NX Open and MBD: A Synergistic Relationship

8.1 Automating MBD Workflows with NX Open

The combination of NX Open and MBD creates particularly powerful automation opportunities. Organizations can use NX Open to:

Automate PMI Application: Custom NX Open scripts can analyze part geometry and automatically apply appropriate PMI — dimensions, tolerances, surface finishes, and notes — based on feature type, material, and manufacturing process. This reduces the time required to fully annotate a model from hours to minutes.
Enforce Standards Compliance: NX Open applications can validate that PMI conforms to organizational standards, customer requirements, and industry specifications such as ASME Y14.5 and ISO 1101, flagging non-compliant annotations for review.
Generate Technical Data Packages: Automated workflows can compile PMI-enriched models, associated documentation, and metadata into complete Technical Data Packages ready for distribution to manufacturing partners and suppliers.
Batch Convert Legacy Drawings: NX Open can orchestrate the Convert to PMI process across large libraries of legacy parts, enabling organizations to systematically migrate their product portfolios to MBD.

8.2 NX Open as the Bridge to AI-Enhanced Workflows

As AI capabilities in NX continue to expand, NX Open provides the programmatic foundation for integrating AI-driven insights into automated workflows. Custom applications can leverage the Copilot’s capabilities, combine AI-generated PMI predictions with rule-based validation, and create feedback loops that continuously improve the accuracy and efficiency of automated processes.

9. Deployment Strategies: Cloud, On-Premise, and Hybrid

9.1 Flexible Deployment Options

Siemens provides maximum flexibility in how organizations deploy NX. The platform can be run on-premise with traditional licensing, through NX X SaaS with cloud management, in virtualized environments, or as a streamed service from public cloud providers. Regardless of deployment method, the features, capabilities, and data compatibility remain identical [27].

9.2 Value Based Licensing: Optimizing Investment

The Value Based Licensing model represents a significant departure from traditional software licensing. Rather than purchasing individual licenses for each add-on module, organizations acquire a pool of floating tokens that can be used across any token-enabled module. When a module is in use, its token value is subtracted from the pool; when the module is closed, the tokens return to the shared pool.

This model is particularly advantageous for organizations with diverse engineering needs. Teams that occasionally require specialized capabilities — such as advanced surface modeling, specific CAD translators, or simulation tools — can access these modules on demand without the cost commitment of perpetual licenses for infrequently used tools.

10. Current Trends and Future Outlook

10.1 The Convergence of AI and CAD

The integration of AI into engineering software is still in its early stages, but the trajectory is clear. As large language models become more capable and domain-specific training data becomes more abundant, AI copilots will evolve from information retrieval assistants to active design participants — suggesting geometry modifications, predicting manufacturing issues, optimizing designs for sustainability, and automating increasingly complex engineering workflows.

Siemens’ investment in AI for NX — from the Design Copilot through the CAM Copilot to embedded features like PMI Prediction and Select Similar — signals a commitment to making AI a practical, value-adding tool rather than a marketing novelty.

10.2 Immersive Engineering: AR/VR in Product Development

The partnership between Siemens and Sony to deliver immersive engineering capabilities represents a new frontier in how engineers interact with designs. NX Immersive Designer provides full NX functionality in virtual and mixed reality, with changes in NX updating instantly in the immersive model and vice versa. Voice-controlled AI interactions allow users to launch commands verbally or consult the Copilot while immersed in a design review [28].

10.3 Sustainability in Engineering

The December 2025 release introduced Design for Sustainability as a purpose-built application that integrates sustainability considerations directly into product design workflows. This capability reflects the growing regulatory and market pressure for manufacturers to consider environmental impact throughout the product lifecycle [29].

10.4 Multi-User Collaborative Authoring

Real-time, multi-user authoring capabilities introduced in recent NX releases break down collaborative barriers by allowing multiple engineers to work on the same design simultaneously. This capability, combined with cloud-connected PLM through Teamcenter, enables truly distributed engineering teams to collaborate as effectively as if they were in the same room.

10.5 The Model Context Protocol (MCP) and Open Integration

The emergence of standardized integration protocols such as the Model Context Protocol is creating new opportunities for connecting NX with external AI systems, data sources, and automation platforms. MCP provides a universal interface for tool integration, enabling AI agents to interact with CAD systems, PLM databases, and engineering tools through standardized, secure connections. This standardization reduces the integration burden and enables more sophisticated multi-system automation workflows [30]. For what an MCP server for NX is and what exists in 2026, see our dedicated page on the Siemens NX MCP server.

11. Implementation Roadmap: Getting Started with NX Open and MBD

Organizations considering NX Open automation or MBD adoption should follow a structured approach:

Assessment Phase: Thoroughly assess current engineering workflows, identifying repetitive tasks, error-prone processes, and bottlenecks that represent the highest-value automation targets.
Pilot Projects: Start with focused pilot projects — such as automating standard drawing templates, creating parameterized part families, or annotating a product line with PMI — to build expertise and demonstrate value.
Training and Skill Development: Leverage Siemens’ comprehensive training through the Xcelerator Academy, covering NX Open API programming in multiple languages, MBD methodology, and advanced NX capabilities.
Scaling and Enterprise Deployment: Progressively expand the automation portfolio, establish coding standards and best practices, and build internal centers of excellence for NX customization.

NX Open automation carries forward into future NX releases when it is maintained: compiled programs are rebuilt and re-signed for each new NX version.

12. Conclusion: The Strategic Imperative

The convergence of NX Open programmability, the expanding add-on ecosystem, Model-Based Definition, AI-powered design assistance, and cloud-connected PLM creates a platform that is uniquely positioned to address the challenges facing modern manufacturing. Organizations that embrace these capabilities gain competitive advantages that compound over time — faster design cycles, fewer errors, better knowledge retention, smoother collaboration, and more agile response to market demands.

Siemens NX is no longer simply the most powerful CAD system on the market. With over 140 add-on modules, comprehensive AI integration, immersive engineering capabilities, and the deepest PLM integration in the industry, it has become the central platform for end-to-end digital transformation in manufacturing. For organizations serious about the future of engineering, the question is not whether to invest in these capabilities, but how quickly they can begin.

NX Open is not just an API — it is the foundation for building intelligent, automated, and future-proof engineering workflows that scale with your organization.
inteliScience

Frequently asked questions about NX Open

What is NX Open in Siemens NX?

NX Open is the official application programming interface of Siemens NX. Programs use it to work with the NX session, parts, features, drawings, PMI and attributes, so tasks that engineers repeat by hand in NX can run as code. Siemens documents it in the NX Open Programmer’s Guide and the NX Open reference for each release.

Which programming languages does NX Open support?

NX Open supports C# and Visual Basic on .NET, C++, Java and Python. NX records journals in C#, Visual Basic and Python. Siemens recommends .NET Core for new .NET programs and has deprecated the replay of Visual Basic journals, so new automation usually starts in C# or Python.

What is the difference between an NX journal and an NX Open application?

An NX journal is a script that NX runs from source, started from the Developer tab (Journal group, Play) or in batch with run_journal; it needs no compilation and no signature. An NX Open application is compiled into a DLL, EXE or JAR, can have its own dialogs built with Block UI Styler, and must be signed before it runs on machines without an NX Open Author license.

Do you need a special license to use NX Open?

Journals run without an NX Open Author license; they only need the NX licenses for the functions they call. Developing and signing compiled NX Open applications requires an NX Open Author license, and an unsigned compiled application runs only where that license is available.

Is NX Open the same as the UF (Open C) API or Knowledge Fusion?

No. NX Open is the object-oriented API. UF, also called Open C, is the older C function library with functions such as UF_MODL_create_extruded; it is still available and can be called from NX Open through UFSession. Knowledge Fusion is a separate rule language for knowledge-driven design inside NX. New automation is usually written against NX Open.

Can AI write NX Open code for Siemens NX?

Yes, for scaffolding. Current language models write NX Open journals that often compile, but they also invent methods and enums that do not exist, so every generated journal needs a check against the NX Open reference and a test in a real NX session. Typical errors and how to catch them are collected in NX Open AI code generation.

References

[1] Frost & Sullivan Frost Radar Analysis, PLM Industry MCAD Tools, 2025.

[2] Siemens Digital Industries Software, “December 2025 Release | Designcenter NX,” NX Design Blog, December 2025.

[3] Siemens, “NX X Value Based Licensing Add-On Modules,” Siemens Xcelerator, 2025.

[4] Siemens Xcelerator Academy, “NX Customization and Programming using NX Open API,” 2025.

[5] NX Journaling Community, “Full Command List,” nxjournaling.com, 2026.

[6] Siemens, “NX Programming and Customization,” Product Data Sheet.

[7] Designfusion, “NX CAM Feature-Based Machining,” designfusion.com.

[8] Applied CAx, “NX Open – Customization & Automation Services,” appliedcax.com, 2025.

[9] Siemens, “Add-ons for NX CAD Software,” Siemens Xcelerator, 2025.

[10] Siemens, “What’s New In Designcenter NX – June 2025,” siemens.com, 2025.

[11] Siemens, “Siemens brings AI copilot, immersive design and integrated fluid and thermal simulation to NX,” Press Release, July 2025.

[12] ENGtechnica, “Siemens NX Gets Big Update in 2025,” engtechnica.com, August 2025.

[13] Siemens, “What’s New In NX | Model-Based Definition and NX Inspector,” NX Design Blog, May 2025.

[15] Siemens, “Model-based definition (MBD) – NX CAD,” siemens.com.

[17] Siemens, “NX | How to move from drawing-based engineering to MBD,” NX Design Blog, February 2026.

[18] Digital Engineering 24/7, “Siemens Brings AI Copilot, Immersive Design to NX,” July 2025.

[19] DRWE, “Model Based Definition in Siemens NX,” drwe.de, September 2025.

[20] Siemens, “Core Capabilities | What’s New in Designcenter NX | December 2025 release,” NX Design Blog, December 2025.

[21] Siemens, “AI enabled design | What’s New in Designcenter NX | December 2025 release,” NX Design Blog, January 2026.

[22] Engineering.com, “Siemens NX is getting an AI copilot for CAM,” September 2025.

[23] Siemens, “Siemens brings AI copilot to NX,” Press Release, July 2025.

[24] Siemens, “What’s new in NX | June 2025 | Managed Mode,” NX Design Blog, August 2025.

[25] NVIDIA Developer Blog, “Building Photorealistic Digital Twins With Siemens Teamcenter Digital Reality Viewer,” June 2025.

[26] Siemens Tecnomatix Blog, “Washington Post features how Siemens digital twin technology is helping reimagine the future of modern manufacturing,” December 2025.

[27] Siemens, “NX CAD bundles & deployment options,” siemens.com.

[28] ENGtechnica, “Siemens NX Gets Big Update in 2025,” August 2025.

[29] Siemens, “December 2025 Release | Designcenter NX,” NX Design Blog, December 2025.

[30] Anthropic, “Introducing the Model Context Protocol,” anthropic.com, November 2024.

Why companies choose inteliScience for NX Open and AI

We design and implement engineering automation solutions that operate under strict quality, compliance, and reliability requirements.

NX Open development and custom add-in engineering
Model-Based Definition consulting and implementation
AI strategy and integration for engineering workflows
Siemens NX and Teamcenter solutions
Private AI and agentic systems for manufacturing
Long-term maintenance and optimization

Our focus is on building engineering platforms that companies can scale and operate for years.

Need NX Open automation or AI-driven engineering solutions?

Let’s talk. If your organization needs custom NX Open development, MBD implementation, or AI-integrated engineering workflows, inteliScience can design and deploy a tailored solution.

Two practical starting points: our NXOpen training with Python gets your engineers writing their first tools, and our NXOpen developers on demand start with a two-week trial sprint on one of your real tasks.

Contact us to receive a technical assessment and implementation roadmap.