Advanced .NET Software Engineer (Systems Modernization)

Growth Acceleration Partners•Colorado Springs, CO

3d•Remote

About The Position

We are seeking an Advanced .Net Software Engineer to join the Customer Success Platform team, responsible for maintaining, stabilizing, and incrementally modernizing critical internal systems supporting customer care, billing/refund workflows, and support operations across TaxAct and Drake. This role is highly platform-and-backend-leaning, requiring an engineer who thrives on diving into complex, inherited enterprise codebases spanning both legacy and modern Microsoft stacks. Rather than defaulting to a rewrite, you will focus on operational safety, system mapping, and making targeted code and data improvements. You will also use agentic AI tools like Claude Code responsibly to accelerate codebase discovery, documentation, and production debugging.

Requirements

3+ years of professional experience in C#/.NET engineering, with a verified history of maintaining, stabilizing, or modernizing legacy enterprise applications. (5+ years of experience with independent ownership of inherited production platforms required for Senior calibration).
Deep experience performing data-driven debugging, troubleshooting production incidents, and working directly with complex database architectures.
Proven experience writing technical documentation, developer runbooks, or cross-system architecture maps.
Experience collaborating directly with non-engineering stakeholders, internal business units, or Help Desk operations.
Advanced mastery of C# within both .NET Framework 4.8 and modern .NET 8 architectures.
Practical development exposure to ASP.NET MVC, ASP.NET Web API, WebForms, ASMX services, and VB.NET application patterns.
Strong SQL Server competence, including building/debugging complex stored procedures, data migrations, and working with Dapper, EF6, or ADO.NET-style data layers.
Proficiency using modern AI-assisted engineering tools (specifically Claude Code, Cursor, or OpenAI Codex) to map code structures and accelerate debugging.
Experience analyzing production environments using structured application logs, metrics tracking, and platform tools (Datadog, Splunk, NLog, or log4net).
Competence navigating Azure DevOps configurations, pull requests, deployment pipelines, and environment variables.
Advanced English proficiency with strong written and verbal technical communication skills.
Exceptional "system archeology" mindset—comfortable operating with incomplete documentation, navigating technical debt, and learning through discovery.
Outstanding plain-language translation skills to effectively collaborate and explain system behaviors to non-engineering business stakeholders.
Pragmatic engineering judgment: a clear focus on triage safety, risk mitigation, rollback planning, and knowing exactly when to fix versus when to escalate.

Nice To Haves

Familiarity with legacy UI patterns (Razor, jQuery, Bootstrap) paired with exposure to modern web libraries like Vue 3, TypeScript, and Vuetify.
Experience managing identity and access systems involving Okta, OIDC, claims-based authorization, shared auth cookies, and cross-application session states.
Exposure to foundational cloud services (AWS Systems Manager Parameter Store, Secrets Manager, CloudWatch, S3, EC2, CodeDeploy, or similar).
Prior experience with background services, polling workers, Topshelf, scheduled batch processing, or Windows Services.
Custom WordPress integration exposure, including custom plugins, WP Engine operations, or REST API connections.
Experience in tax preparation systems, fintech, payment gateways, or highly compliance-heavy industries.

Responsibilities

Maintain, debug, and enhance business-critical customer support applications, expert-help systems, and billing/refund management portals.
Support the platform's strategic absorption of newly inherited systems by systematically identifying hidden dependencies, hosting environments, database structures, and support paths.
Diagnose and resolve complex production incidents across application logic, SQL Server schemas, authentication boundaries, and IIS deployment environments.
Drive the incremental modernization of legacy applications, specifically focusing on upgrading authentication frameworks, session state management, observability, and deployment pipelines.
Author comprehensive runbooks, technical documentation, and triage guides to capture system knowledge and reduce future cognitive load across the engineering group.
Collaborate cross-functionally with Engineering, Product, Help Desk, IT/Networking, and Customer Success partners to isolate and solve boundary-crossing system flaws.
Integrate agentic development tools (Claude Code) into your workflow to rapidly explore unfamiliar repositories, reverse-engineer undocumented logic, and scaffold automated regression coverage.