Senior C#/.NET Technical Lead

Senior C#/.NET Technical Lead
Location: Primarily remote, but candidates must be located in Minnesota and willing to go onsite at Best Buy in the Bloomington/Richfield area as needed. There may be weeks where 1 2 days onsite are required.
Position Overview
Client is looking for a highly experienced, hands-on Senior C# Technical Lead who can become the technical owner of the Client POS codebase.
This is not a role for someone whose first instinct is to completely rewrite a legacy platform. The ideal candidate has experience taking ownership of a large, mission-critical .NET environment and modernizing it incrementally and safely, while protecting production stability and identifying opportunities to introduce newer technologies where appropriate.
This person will need to get deep into the codebase, understand dependencies and downstream impacts, make technical recommendations, improve documentation/processes, and communicate directly with Client stakeholders as well as offshore/onshore development teams.
POS Environment
The POS ecosystem supports critical retail functions including:

• Tender and payment processing
• Returns
• Loyalty
• Finance plans
• EMV/payments
• Enterprise applications including APTool, Customer Profile and Purchase History
• REST APIs including PriceMatch, SubmitReturn, AutoRefund, ConsumerPos and RepairTracker

Core technologies include:

• C#
• .NET Framework 4.8
• .NET 10
• .NET Standard 2.0
• ASP.NET Core APIs
• WCF
• Windows Workflow Foundation
• SQL Server
• ADO.NET
• Angular 21.x
• TypeScript 5.x

The environment also includes shared Common, Hosting and POS business layers, the E3Workflow engine, and multiple enterprise/client UI applications.
Must-Have Experience

• Deep C# and .NET Framework 4.x experience
• Hands-on experience modernizing/migrating legacy applications to .NET 6/8/10
• Experience with multi-targeting, .NET Standard 2.0 and package/dependency conflicts
• Strong WCF experience, including bindings, configurations, contracts and debugging
• SQL Server and ADO.NET
• Comfortable working with stored procedures and DataSets
• MSBuild, NuGet and PowerShell build scripting
• Azure DevOps pipelines
• Proven track record of releasing changes safely into large, mission-critical production environments
• Ability to troubleshoot complex legacy systems and understand downstream/regression risk
• Strong hands-on technical leadership, architecture, code review and debugging skills
• Strong written and verbal communication
• Experience working across offshore and onshore development teams
• Comfortable communicating directly with Best Buy
• Willing and able to go onsite when needed

Nice to Have

• Windows Workflow Foundation 4 / XAML
• Retail Point of Sale experience
• Retail payments / EMV / tender processing
• Store-and-forward functionality
• PCI DSS awareness
• Angular / TypeScript
• ASP.NET Core
• Core WCF
• OpenID Connect / authentication
• Checkmarx remediation
• TeamCity
• Workflow/state-machine applications
• POS hardware/device integrations such as payment terminals, printers, scanners or cash drawers

What They Are Really Looking For
The ideal candidate has previously taken ownership of a large .NET Framework system that remained actively used in production while being modernized.
They want someone who:

• Understands the existing architecture before recommending major changes
• Modernizes incrementally rather than pushing a big-bang rewrite
• Thinks through what could break before making changes
• Can confidently own technical decisions around the codebase
• Remains hands-on with development and troubleshooting
• Helps guide other developers through implementation and debugging
• Improves documentation, architecture and development processes
• Can balance modernization with the stability required for a major retail POS system
• Is comfortable working directly with OSI Digital and Best Buy stakeholders

Retail/POS experience is a strong plus , but candidates from other highly transactional or mission-critical environments can still be considered if their C#/.NET Framework modernization and WCF experience is strong.