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Senior Full Stack .NET Developer (Legacy Modernization)

Pay Rate: $22.50-$30/hour

Position Overview

We are seeking a highly skilled Senior Full Stack .NET Developer to support the modernization of critical business applications and the migration of a legacy platform. This role requires a hands-on engineer with deep experience in ASP.NET Web Forms (ASPX), VB.NET, SQL Server, React, and .NET Core/.NET who can effectively bridge legacy technologies with modern application architectures.

In addition to strong technical capabilities, this position requires exceptional leadership, communication, and emotional intelligence. The successful candidate will work within an evolving environment where legacy systems are being modernized and will play a key role in helping guide the transition while maintaining positive collaboration across technical teams.

Experience working in highly regulated industries where application reliability, data integrity, compliance, and auditability are critical is highly desirable.

Key Responsibilities

- Support, maintain, and enhance existing ASP.NET Web Forms (ASPX) and VB.NET applications.
- Analyze legacy applications and develop modernization strategies aligned with business and technical objectives.
- Lead and execute migrations from legacy Microsoft technologies to modern architectures using React and .NET Core/.NET.
- Design, develop, test, and deploy scalable full-stack solutions.
- Develop and optimize SQL Server databases, queries, stored procedures, and performance tuning initiatives.
- Partner with business stakeholders, architects, and development teams to define technical requirements and implementation plans.
- Ensure data integrity, system reliability, and application security throughout modernization efforts.




- Troubleshoot production issues and implement sustainable solutions.
- Provide technical leadership and mentorship to team members throughout modernization initiatives.
- Promote development best practices, coding standards, and maintainable application design.
- Support change management efforts and help facilitate a smooth transition from legacy technologies and processes.
- Participate in code reviews, architecture discussions, and technical planning sessions.

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Required Qualifications

- Demonstrated experience in full-stack software development across both legacy and modern Microsoft technology stacks.
- Strong hands-on experience with:
- ASP.NET Web Forms (ASPX)
- VB.NET
- C#
- SQL Server
- React
- .NET Core / Modern .NET

- Proven experience supporting, enhancing, and modernizing legacy applications.
- Experience designing, developing, and maintaining full-stack enterprise applications.
- Strong understanding of software architecture, design patterns, and application modernization strategies.
- Experience developing and consuming RESTful APIs.
- Advanced SQL development skills, including database design, query optimization, performance tuning, and troubleshooting.
- Experience supporting business-critical production applications.
- Strong analytical, troubleshooting, and problem-solving abilities.




- Excellent communication and collaboration skills with the ability to work effectively across technical and non-technical teams.
- Demonstrated leadership capabilities, including the ability to guide teams through organizational and technical change.

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Preferred Qualifications

- Experience leading application modernization initiatives.
- Experience working within regulated industries such as healthcare, medical devices, pharmaceuticals, financial services, insurance, manufacturing, or government.
- Familiarity with cloud platforms such as Azure or AWS.
- Experience with CI/CD pipelines and DevOps practices.
- Exposure to containerization technologies and modern deployment strategies.
- Experience with automated testing frameworks and application monitoring tools.

Critical Success Factors Legacy Modernization Expertise
- Ability to assess legacy systems and develop practical modernization roadmaps.
- Strong understanding of both legacy Microsoft technologies and modern web application frameworks.

Leadership & Emotional Intelligence
- Exceptional interpersonal and relationship-building skills.
- Ability to navigate sensitive organizational transitions professionally and diplomatically.
- Proven experience influencing technical teams and stakeholders through change.

Data Integrity & Quality Focus
- Strong appreciation for data accuracy, auditability, and system reliability.
- Experience working in environments where errors can have significant business or regulatory impact.

Ownership & Execution
- Ability to work independently and take ownership of complex initiatives.
- Strong focus on delivering business value while balancing technical debt reduction and modernization objectives.

📌 Senior Full Stack .NET Developer (Ciudad de México)
🏢 SCIGON
📍 Ciudad de México