Senior Software Engineer – Legacy Codebase Migration

Job not on LinkedIn

🔥 12 hours ago

🗽 New York – Remote

🗽 New York – Remote

💵 $180 / hour

⏳ Contract/Temporary

🟠 Senior

🧑‍💻 Full-stack Engineer

👻 Ghost score 0%

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24-MAG

WebsiteLinkedInAll Job Openings

2 - 10 employees

🤝 B2B

💼 Consulting

B2B • Consulting

24-MAG is a commercial strategy and execution firm that helps B2B organizations design and implement systems, workflows, and operating rhythms for sales, client management, and cross-functional projects. They focus on transforming scattered processes into aligned, measurable, and scalable commercial functions—covering pipeline structure, account management frameworks, and operational discipline for teams seeking efficient, intentional growth.

📋 Description

• Design, implement, review, and evaluate complex codebase migration and modernisation tasks • Analyse mature production systems and determine safe, technically sound migration approaches • Review legacy application architecture, dependencies, APIs, databases, build systems, and infrastructure • Identify technical debt, compatibility constraints, migration risks, and hidden dependencies • Develop migration strategies for large, interconnected production environments • Evaluate language, runtime, framework, application, database, data-layer, infrastructure, cloud, CI/CD, build-tool, API, integration, authentication, identity, repository, dependency, toolchain, and testing migrations • Assess behavioural equivalence, compatibility, data integrity, security, performance, production reliability, maintainability, and production readiness • Review deployment architecture, operational dependencies, scalability, staged rollout, rollback, observability, and resilience strategies • Analyse unfamiliar codebases and diagnose subtle migration failures • Evaluate proposed technical decisions against realistic enterprise constraints • Identify missing dependencies, edge cases, regression risks, and unsafe assumptions • Provide clear, technically rigorous feedback on migration approaches and implementations

🎯 Requirements

• 5+ years of professional software engineering experience, ideally at Senior, Staff, Principal, Lead, or equivalent level • Significant hands-on experience executing large-scale production migrations • Personally owned or made substantial technical contributions to complex modernisation initiatives • Strong experience with mature systems involving technical debt, complex dependencies, legacy integrations, and significant regression risk • Strong knowledge of compatibility, testing, observability, staged rollouts, rollback strategies, and behavioural equivalence • Ability to reason deeply about unfamiliar codebases and diagnose subtle migration failures • Experience with one or more major migration categories, including languages, frameworks, databases, APIs, infrastructure, CI/CD, authentication, repositories, testing, or dependencies • Experience modernising systems within financial services, fintech/payments, trading, insurance, healthcare, telecom, large technology companies, or other high-reliability environments is particularly valuable • For mainframe modernisation work, experience with COBOL, z/OS, CICS, JCL, DB2, VSAM, batch processing, and COBOL-to-Java/Python migration is particularly valuable • Must complete work without using confidential or proprietary information belonging to any employer, client, institution, or other third party • H1-B and STEM OPT support is unavailable for this engagement

🏖️ Benefits

• Fully remote • Flexible scheduling based on project requirements • Talent-network opportunity with potential for ongoing project work