Trilon Group

Infrastructure consulting for transportation and water

Senior CAD Plugin Developer

Desktop Application DevelopmentUpdated on Nov 13

Full-timeRemote in USA$120k - $185k /yrRemote

About the Job

Requirements

At least 6 years of professional software development experience, including at least 4 years building and shipping production CAD plugins or extensions.
Strong C# and .NET skills, with working knowledge of C/C++ for native CAD APIs.
Deep experience with AutoCAD and Civil 3D APIs, plus hands-on experience with the MicroStation SDK or one or more Bentley OpenX Designer SDKs.
Working knowledge of civil design workflows, including how roadway, drainage, grading, or site designers progress from survey through model to plan set, what they reuse across projects, and where time is spent.
Experience calling REST and GraphQL APIs from desktop applications, including OAuth 2.0 / OpenID Connect sign-in and secure token storage.
Experience with coordinate systems, map projections, and spatial data formats such as LandXML, GeoJSON, shapefiles, and geodatabases.

Responsibilities

Design, build, and ship production plugins for AutoCAD / Civil 3D using .NET and ObjectARX, and for MicroStation / OpenX Designer SDKs using .NET and native SDKs.
Build the end-to-end design export flow from the plugin to the platform, including desktop sign-in through OAuth 2.0 / OpenID Connect, tokens that persist between sessions, design packaging, upload through platform APIs, and handling partial failures and retries.
Build the design import path so users can browse designs by project, select files, and download them into the CAD session through secure, time-limited links.
Extract and convert civil objects—including alignments, profiles, corridors, surfaces, pipe networks, and feature lines—and their coordinate systems into open formats such as LandXML, IFC, and GeoJSON without data loss.
Build ArcGIS Pro add-ins and integrations that synchronize CAD spatial data with ArcGIS, including styles, spatial reference files, and OGC-standard services.
Work directly with civil designers to observe their workflows and shape when and how the plugin requests their attention; validate output against real projects before release.
Add usage and error events to plugins to measure export and import performance in the field.
Own installers, code signing, versioning across yearly Autodesk and Bentley releases, and deployment to engineers’ machines.
Partner with platform engineers on REST and GraphQL APIs, plugin storage dependencies, and third-party service integrations.
Set plugin architecture and coding standards, review code, and mentor developers on CAD and GIS APIs.

Desired Qualifications

Experience with the ArcGIS Pro SDK, ArcGIS REST APIs, Arcade, or QGIS development.
Experience with PostgreSQL / PostGIS or other spatial databases.

Trilon is building a digital platform that gives engineers one place to manage, share and reuse their design data. The desktop tools our engineers use every day, Autodesk Civil 3D, the Bentley OpenX family (OpenRoads, OpenRail, OpenSite, OpenComms) and Esri ArcGIS Pro, need to connect to that platform directly.

As our Senior CAD Plugin Developer, you will own those connections. You will design and build the plugins that let an engineer export a design from their CAD tool into the platform, bring designs back by project, and keep spatial data in sync with ArcGIS. You will set the technical direction for our plugin work and be the team’s expert on CAD and GIS APIs and civil design data.

The hard part of this job is less the CAD APIs and more how designers actually work: when they save, what they reuse, where a plan set comes from, and what they will tolerate inside a design session. You will spend real time with civil designers so the plugins fit their workflow instead of interrupting it.

Build the plugins. Design, build and ship production plugins for AutoCAD / Civil 3D (.NET, ObjectARX) and MicroStation / OpenX Designer SDKs (.NET and native SDKs).
Own the export path. Build the end-to-end flow from a click in the plugin to the platform: sign-in through the platform (OAuth 2.0 / OpenID Connect from a desktop app, with tokens that persist between sessions), packaging the design, upload through platform APIs, and handling partial failures and retries.
Build the import path. Let users browse designs by project, pick files and download them into the CAD session through secure, time-limited download links.
Get the data right. Extract and convert civil objects (alignments, profiles, corridors, surfaces, pipe networks, feature lines) and their coordinate systems into open formats such as LandXML, IFC and GeoJSON, without losing data.
Connect to GIS. Build ArcGIS Pro add-ins and integrations that sync CAD spatial data with ArcGIS, including styles, spatial reference files and OGC-standard services.
Fit the designer’s workflow. Sit with civil designers, watch how they work in a session, and shape when and how the plugin asks for their attention. Validate output against real projects before it ships.
Instrument what you ship. Add usage and error events to the plugins so we can see how export and import perform in the field.
Package and support. Own installers, code signing, versioning across yearly Autodesk and Bentley releases, and deployment to engineers’ machines.
Partner with platform engineers. Work with the platform team on the REST and GraphQL APIs and the storage the plugins call, and on any third-party service integrations the plugins depend on.
Lead technically. Set plugin architecture and coding standards, review code, and mentor other developers on CAD and GIS APIs.

6+ years of professional software development, with at least 4 years building and shipping CAD plugins or extensions used in production.
Strong C# and .NET, and working C/C++ for native CAD APIs.
Deep experience with the AutoCAD and Civil 3D APIs; hands-on experience with the MicroStation SDK or one or more of the Bentley OpenX Designer SDKs (OpenRoads, OpenRail, OpenSite, OpenComms).
Working knowledge of civil design workflows and processes: how roadway, drainage, grading or site designers move from survey to model to plan set, what they reuse across projects, and where the time goes.
Experience calling REST and GraphQL APIs from desktop applications, including OAuth 2.0 / OpenID Connect sign-in and secure token storage.
Experience with coordinate systems, map projections and spatial data formats (LandXML, GeoJSON, shapefiles, geodatabases).
ArcGIS Pro SDK, ArcGIS REST APIs, Arcade, or QGIS development.
PostgreSQL / PostGIS or other spatial databases.

About the Company

Trilon Group

Infrastructure consulting for transportation and water

Trilon Group provides infrastructure consulting in transportation, water, and municipal systems in the Mid-Atlantic region. It works by partnering with local governments, municipalities, and private clients to deliver planning, design support, and project management through fee-based engagements, expanding capabilities through alliances with firms like Rinker Design Associates and Wilson Engineers. The company differentiates itself with a platform-style growth approach backed by private equity and a People First culture focused on talent development. Its goal is to expand service offerings and market presence in the Mid-Atlantic by building scalable partnerships and using capital to support growth.

Company size: 51-200
Company stage: Growth Equity (Non-Venture Capital)
Total funding: $200M
Headquarters: Denver, CO
Founded: 2021

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