Tekla Open API: what you can automate in Tekla Structures and how plugins get built
Zakhar Vityk, CEO, Consedge Tech
Tekla Structures ships with a deep toolset, and fabricators and detailers still lose hours to the parts of the job that are unique to them: house connection rules, numbering checks, drawing conventions, exports to the shop. The Tekla Open API is how those parts get automated.
This guide covers what the API reaches, how to choose between a custom component, a macro, a plugin and an application, what changed for developers in recent releases, and what to plan before Tekla plugin development starts.
What the Tekla Open API covers
The Tekla Open API is a set of .NET libraries, used mostly from C#. The main areas:
- Model. Create, read and modify parts, bolts, welds, reinforcement, assemblies and user-defined attributes.
- Drawings. Create and edit drawings, views, dimensions, marks and text.
- Catalogs. Profiles, materials, shapes and components.
- Selection and filters. Find objects by rules, or ask the user to pick.
- Reports. Read the same properties that report templates use.
Since Tekla Structures 2026, Tekla Model Sharing is part of the Open API as well.
Four ways to extend Tekla
| Form | What it is | When to use it |
|---|---|---|
| Custom component | Built in the component editor, no code | A repeating connection or detail with moderate logic |
| Macro | A C# script that runs inside Tekla | A short sequence of interface or model actions |
| Plugin | Compiled, parametric, stored in the model, re-runs when inputs change | Details and objects that must follow the model and have their own dialog |
| Application | A separate program connected to the running model | Batch checks, exports, integrations, dashboards |
A useful rule: start at the top of the table and move down only when you hit a wall. A custom component that does the job is cheaper to own than a plugin.
The same rule as a path: the first yes is the form to build.
Trimble calls applications built on the Open API extensions. They are packaged as TSEP files and can be distributed through Tekla Warehouse.
What changed for developers in recent releases
Three releases reshaped the ground under older tools.
Tekla Structures 2024. Tekla and the Open API moved to .NET Framework 4.8, and the API libraries became compatible with .NET Standard 2.0. COM support was removed from the Open API assemblies, and they are no longer registered in the Global Assembly Cache. The 2024 release notes list the details.
Tekla Structures 2025. The signing of extension packages was reworked, and Trimble added a Developer Assistant that drafts Open API code from its documentation.
Tekla Structures 2026. Only 64-bit extension packages are supported.
The practical result: a tool built years ago against old assemblies, with a COM dependency or a reference to the GAC, needs a rebuild and a retest. The fix is the same pattern we describe for Revit add-ins on .NET 10: reference the API from NuGet, one package set per Tekla version, and build every supported version from one codebase.
What fabricators and detailers automate
- Connections and details by house rules. Plugins that place and size details the way the shop builds them, not the way the default component does.
- Checks before issue. Applications that verify numbering, attributes, materials and missing data across the model, and list what must be fixed.
- Drawing conventions. Tools that apply the firm's dimensioning, marks and layout rules after drawings are created.
- Exports to the shop and the office. Bills of materials, NC data and status fields sent to production or ERP systems without retyping.
- Model data for others. Attributes and status pushed to coordination platforms, schedules or dashboards.
Before building any of these, search Tekla Warehouse. If an extension already does the job, use it. Custom development earns its cost where the rule is yours alone.
It is also worth watching what Trimble adds. Tekla Structures 2026 updated its AI-assisted cloud service for fabrication drawings. Custom drawing tools should target the conventions that remain specific to your firm.
Engineering notes: what bites in practice
Commit deliberately. Changes reach the model when they are committed. Batch related changes and commit once, so the user gets one consistent result.
Select with filters. Looping over every object in a large model is slow. Filter expressions let Tekla do the search.
Plugins re-run. A plugin executes again whenever its inputs change. It must be fast, give the same result for the same input, and never leave side effects outside what it creates.
The Drawings API has gaps. Not everything a user can do in the drawing editor is available to code. Check the specific operation before promising a drawing feature.
Environments differ. Profile and material names change between regional environments. Test in the customer's environment and on the customer's model.
Shared models. A tool that works on a single-user model needs its own test with Model Sharing or multi-user mode.
A new version every year. Each Tekla release, and some service packs, need a build and a test pass.
How we work on Tekla projects
Consedge Tech builds on the Tekla Open API alongside Revit, Siemens NX and SolidWorks. Tekla plugins are among the tools we have delivered.
A Tekla project with us starts the same way as any other: with the workflow, a sample model and the drawings you issue today. If you have a task in mind, book a Feasibility Review. You get a written verdict on what the API allows, where the gaps are, and what a production tool involves. More on our approach is on the plugin development page.
FAQ
Which language does the Tekla Open API use?
It is a .NET API. Most tools are written in C#.
When do I need a plugin instead of a custom component?
When the logic outgrows what the component editor can express, when you need your own dialog, or when the tool must read data from outside the model.
Will my extension work in the next Tekla version?
Plan a rebuild and a test pass for every major version. Tools built before the 2024 release usually need code changes as well.
Can a Tekla tool exchange data with ERP or production software?
Yes. An application can read the model and write to another system through that system's API or file formats, and write status back into Tekla attributes.
Working on something like this?
Thirty minutes with the engineers who would build it, then a written verdict — including “don’t build this” where that is the answer.
- First call free, no obligation
- Straight answers
- Fixed-price written verdict
- Senior engineers, not account managers