Senior Legacy Codebase Migration Engineer

Mercor; United States; Remote; USD 180,000 - 250,000; Full time

Job summary

Mercor is partnering with a frontier AI research lab to engage experienced software engineers specializing in legacy codebase migration and modernisation. You will work on designing and executing migrations across large, production-grade systems in sectors such as financial services, fintech/payments, and healthcare.

The role emphasizes hands-on experience with production migrations, with opportunities to apply migration expertise to real-world, mission-critical enterprise environments.

Qualifications

• Experience migrating large, production-grade systems across enterprises.
• Strong understanding of compatibility, testing and rollback strategies.
• Ability to reason about unfamiliar codebases and diagnose migration failures.
• Experience modernising core banking, payments, trading, insurance, healthcare, telecom or other high-reliability systems.

Responsibilities

• Design, implement, review, and evaluate complex codebase migration and modernisation tasks.
• Analyse legacy code, dependencies, APIs, databases, build systems, and infrastructure for safe migrations.
• 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.

Skills

Legacy code migration

Production migrations

Codebase analysis

Testing strategy design

Migration validation

Tools

Java 8-17/21

.NET

Python 2-3

PHP 7-8

Angular

Django

Spring/Spring Boot

ASP.NET

Next.js/Astro

PostgreSQL

ORMs: Hibernate/jOOQ/Sequelize/Prisma

Docker/Kubernetes

CI/CD: GitHub Actions

Maven/Gradle

GraphQL/gRPC

Job description

Mercor is partnering with a frontier AI research lab to engage experienced software engineers specializing in legacy codebase migration and modernisation. You will work on designing and executing migrations across large, production-grade systems in sectors such as financial services, fintech/payments, and healthcare.

The role emphasizes hands-on experience with production migrations, with opportunities to apply migration expertise to real-world, mission-critical enterprise environments.