Legacy Codebase Migration Expert

About this role

Mercor is partnering with a **frontier AI research lab** to engage experienced software engineers with deep expertise in **legacy codebase migration and modernisation**. We are looking for engineers who have personally executed complex migrations across **large, production-grade systems**, particularly in **financial services, fintech/payments, insurance, healthcare, telecom, large technology companies, and other mission-critical enterprises**. Strong hands-on experience with production migrations is the primary qualification. ## What You'll Do - Design, implement, review, and evaluate complex **codebase migration and modernisation tasks**. - Analyse legacy code, dependencies, APIs, databases, build systems, and infrastructure to determine safe migration approaches. - Preserve **functionality, backwards compatibility, data integrity, security, and performance** during migrations. - Develop tests and validation strategies to identify migration regressions and behavioural differences. - Evaluate AI-generated migration solutions for **correctness, completeness, maintainability, and production readiness**. ## Relevant Migration Experience Candidates should have deep expertise in **one or more** of the following: - **Language/version:** Java 8 → 17/21, legacy .NET → modern .NET, Python 2 → 3, PHP 7 → 8 - **Language rewrites:** COBOL → Java/Python, JavaScript → TypeScript - **Frameworks:** Angular, Rails, Django, Spring/Spring Boot, ASP.NET, Next.js/Astro, and other major framework upgrades/replacements - **Databases & ORMs:** Oracle/MySQL → PostgreSQL, SQL → NoSQL, Hibernate → jOOQ, Sequelize → Prisma, raw SQL → ORM - **Infrastructure:** VMs/bare metal → containers, Docker/Kubernetes, cloud-native architectures - **CI/CD:** Jenkins/Travis → GitHub Actions, GitLab CI, or modern deployment pipelines - **Build/package tooling:** Maven → Gradle, Webpack → Vite, CRA → Next.js, npm → pnpm - **APIs:** REST → Graph