Civil 3D API & Plugin Development in C# .NET
Professional Civil 3D plugins built on the Civil 3D .NET API: custom commands, palettes and batch tools that work directly with alignments, profiles, corridors, surfaces, pipe networks, parcels and labels.
Plugins that understand civil objects
Civil 3D objects are more than AutoCAD geometry. An alignment has stations and design criteria, a corridor has baselines, regions and assemblies, and a pipe network has parts lists and rules. The Civil 3D .NET API exposes these objects, so plugins can create and edit civil design data and read results such as surface elevations, station offsets and volumes.
ENGIMANDI writes Civil 3D plugins in C# that combine the Civil 3D and AutoCAD APIs with WPF user interfaces and external data. We handle Civil 3D-specific details such as styles and label styles, object IDs and transactions, drawing settings, coordinate systems and version compatibility. Plugins are delivered as signed, versioned bundles that load automatically for your whole team.
Related: AutoCAD .NET API development.
What you get
- C# .NET Civil 3D plugins
- Commands, ribbons & palettes
- Alignment & profile tools
- Corridor & surface tools
- Pipe & pressure network tools
- Label & style automation
- Autoloader bundles
- Version upgrades & support
What our Civil 3D plugins do
Deep integration with civil design objects.
Alignments & Profiles
Create alignments from data, place profiles and check design criteria.
Corridors
Manage regions, targets, frequencies and assemblies across large corridors.
Surfaces
Build surfaces from survey data, compare them and report volumes and elevations.
Networks
Place and edit pipes and structures, apply rules and export network data.
Labels
Apply label styles in bulk and fix label overlaps and style issues.
Batch Tools
Process many drawings for style updates, data extraction and clean-up.
Plugin stack
Autodesk and .NET tools.
Typical projects
- Road alignment creation from setting-out tables
- Invert and cover checker for sewer networks
- Surface volume report per construction stage
- Corridor frequency and target manager
- Bulk label style replacement in old drawings
- Upgrade of an old plugin to the latest Civil 3D
How we build Civil 3D plugins
Specify
Commands, data and user workflow.
Prototype
Core API logic proven on your drawings.
Develop
UI, error handling and settings.
Test
Real project data and versions.
Deploy
Bundles, training and support.
Civil 3D API questions
Can the API create corridors?
Yes. The API can create and edit corridors, baselines and regions, though complex corridors are often built from templates with the API filling in data.
Can plugins read Civil 3D data without opening drawings?
Civil objects need Civil 3D to read them. For batch work, we process drawings with Civil 3D running unattended, or export LandXML for other systems.
Is the source code ours?
Yes. You receive full source code and ownership.
Will plugins survive Civil 3D upgrades?
Most code carries over. We recompile and test for each new version, including the .NET 8 move in 2025 versions.
Can we sell the plugin?
Yes. We can package it for the Autodesk App Store or your own licensing.