Senior .NET Developer (C# / WinForms / SQL Server)

Senior .NET Developer (C# / WinForms / SQL Server) — Desktop Performance + Reliability

Conest develops estimating and project management software used by electrical contractors and data cabling firms. We’re hiring a senior engineer to strengthen our flagship Windows desktop estimating application, used by customers ranging from small shops to high-volume organizations.

The role

This role focuses on a mature C#/.NET WinForms desktop application backed by a SQL database. You’ll partner with an experienced developer to co-own ongoing improvements, including performance at scale, reliability, and release confidence in complex, data-heavy workflows.

• *Primary focus: Windows desktop (WinForms) + SQL. Not a web/front-end UI role.**

What you’ll do

• Diagnose and improve application performance (responsiveness, large datasets, high-usage workflows)
• Write, troubleshoot, and optimize SQL queries and stored procedures used in production
• Debug complex issues in a legacy WinForms application and deliver durable fixes
• Participate in design discussions and code reviews to improve maintainability and reduce regression bugs
• Improve release quality through practical testing and disciplined changes
• Support integrations with external systems/tools (data exchange and workflow connections)
• Contribute to documentation/knowledge transfer so critical system knowledge isn’t trapped in one person

Must-have experience

• Senior-level experience building and supporting Windows desktop business applications
• Strong C#/.NET experience, including WinForms
• Strong SQL skills focused on writing and troubleshooting queries and stored procedures (not DBA administration)
• Proven ability to debug, fix root causes, and prevent regressions
• Collaborative working style: communicates clearly, participates in reviews, and shares context effectively

Nice-to-have

• Profiling and performance tuning experience (desktop and/or SQL)
• Experience improving stability in legacy systems (safe refactoring, reducing recurring defects)
• Familiarity with common desktop product tooling (installers, reporting tools, UI component libraries, etc.)
• Experience building integrations (import/export, APIs, data connectors)
• Experience with version control systems (Git)

Interview process

Our interview process includes a brief, practical C# and SQL exercise (job-relevant; completed live via screen share).

Pay: $120,000.00 - $165,000.00 per year

Benefits

• 401(k)
• 401(k) matching
• Dental insurance
• Employee assistance program
• Flexible spending account
• Health insurance
• Health savings account
• Life insurance
• Paid time off
• Vision insurance

People with a criminal record are encouraged to apply

Application Question(s)

• How many years of WinForms / Windows desktop application experience do you have?
• How often do you write or maintain SQL (queries and/or stored procedures) in production systems?
• Briefly describe a performance problem you diagnosed and fixed. What did you change and how did you validate improvement?
• Briefly describe a complex bug you debugged in a legacy system (root cause + how you prevented recurrence).
• How many years of professional C#/.NET experience do you have?How many years of professional C#/.NET experience do you have?

Work Location: Remote