Sr. Software Developer - Application Migration & Modernization

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Sr. Software Developer - Application Migration & Modernization based in Brazil.

This is a hands-on engineering role focused on modernizing legacy .NET applications and their underlying data platforms. You will transform mature, business-critical systems into maintainable, scalable, and testable solutions. The work spans both application and database layers, including migrating .NET Framework applications from Oracle to PostgreSQL on AWS. You’ll tackle real-world modernization challenges such as undocumented logic, legacy data access patterns, stored procedures, and production constraints. Success requires careful planning, strong testing, and a focus on seamless migrations with minimal disruption to users. You’ll collaborate closely with architects, DBAs, product owners, and engineering teams while helping raise development standards across the team.

Accountabilities:

• Assess existing .NET Framework applications, identifying dependencies, integrations, data access patterns, technical risks, and modernization priorities.
• Develop realistic modernization and migration plans, including sequencing, dependencies, risks, and mitigation strategies.
• Modify application code to support PostgreSQL as the target backend, ensuring the migration goes beyond simply moving the underlying data.
• Modernize and migrate legacy data access layers, including ADO.NET and older Entity Framework implementations, toward current and maintainable patterns.
• Migrate Oracle workloads to PostgreSQL, including schema conversion, PL/SQL-to-PL/pgSQL translation, data type and collation changes, query rewrites, and performance validation.
• Analyze and preserve business logic embedded in legacy database objects such as packages, procedures, triggers, and sequences.
• Develop characterization, integration, and automated comparison tests to validate application behavior and make migrations reliable and defensible.
• Contribute to CI/CD pipelines, deployment automation, monitoring, and observability for modernized applications.
• Collaborate directly with architects, DBAs, product owners, and other stakeholders, translating technical trade-offs into clear business language.
• Document architectural and technical decisions to ensure solutions remain understandable and maintainable.
• Mentor mid-level developers and conduct code reviews with a strong focus on maintainability, quality, and long-term sustainability.

Requirements:

• 10+ years of professional software development experience, with substantial hands-on expertise in C# and .NET.
• Strong current knowledge of .NET Framework 4.8 and legacy technologies including ASP.NET MVC/Web API, Web Forms, WCF, IIS, and Windows Services.
• Proven experience modernizing or migrating existing applications, rather than focusing exclusively on greenfield development.
• Strong relational database expertise, including SQL development and tuning, execution-plan analysis, transactions, and isolation behavior.
• Hands-on experience with Oracle and PL/SQL, including packages, procedures, triggers, and sequences, with the ability to understand business logic embedded in database code.
• Practical experience migrating or adapting applications and databases to PostgreSQL, including data types, queries, schema structures, and performance considerations.
• Experience with source control, branching strategies, and CI/CD tools such as Git, Azure DevOps, GitHub Actions, or comparable platforms.
• Strong analytical and problem-solving abilities, particularly when working with undocumented systems or incomplete requirements.
• Clear communication skills and the ability to explain technical decisions and trade-offs to non-technical stakeholders.
• Collaborative mindset, ownership, and the ability to work effectively in distributed teams.
• Experience mentoring developers and reviewing code with an emphasis on maintainability and engineering quality.

Benefits:

• 100% remote working arrangement.
• Full-time, hourly engagement.
• Initial 2-month contract with the possibility of extension.
• Open to candidates based in Brazil and across Latin America.
• Opportunity to work on complex, production-critical application modernization and cloud migration projects.
• Hands-on exposure to .NET modernization, Oracle-to-PostgreSQL migration, AWS infrastructure, automation, testing, and CI/CD.
• Collaborative environment involving architects, DBAs, product owners, and experienced engineering teams.