Senior Forward-Deployed Engineer — Next.js Legacy Modernization

Hi,

Please review the below JD

Senior Forward-Deployed Engineer — Next.js Legacy Modernization

Location: United States — remote, with occasional customer-site travel

Engagement: Sophus consultant supporting Vercel-led enterprise engagements

Level: Senior, hands-on individual contributor

Role mission

Help enterprise customers modernize legacy Ruby/AWS applications into production-grade Next.js applications running on Vercel.

You will work alongside a named Vercel Forward-Deployed Engineer who provides technical architecture and delivery assurance. You and the Sophus team will execute the assessment, migration, engineering, testing, CI/CD, deployment, and stabilization work.

This is not an advisory-only or front-end UI role. You must be comfortable entering an ambiguous legacy environment, defining an incremental migration path, writing production code, and owning delivery outcomes.

Responsibilities

● Assess legacy Ruby/Rails applications, AWS architecture, dependencies, APIs, data flows, infrastructure, deployment pipelines, and technical debt.

● Translate the assessment into an incremental migration strategy with defined workstreams, risks, acceptance criteria, coexistence patterns, cutover plans, and rollback procedures.

● Modernize legacy front ends and monolithic applications to React, TypeScript, Next.js, and Vercel.

● Build production applications using Next.js App Router, React Server Components, SSR, SSG, ISR, streaming, caching, and personalization.

● Preserve necessary Ruby/Rails and AWS services during staged migration while progressively moving appropriate workloads to Vercel.

● Design and implement CI/CD pipelines, preview environments, automated testing, deployment promotion, observability, and rollback.

● Conduct code, architecture, performance, and Core Web Vitals audits and convert findings into executable roadmaps.

● Work hands-on within enterprise customer codebases and security constraints.

● Lead technical discovery, whiteboarding, workshops, pair programming, documentation, and knowledge transfer.

● Build AI-enabled applications and agentic workflows using Vercel AI SDK, AI Gateway, MCP, agent frameworks, and human-in-the-loop patterns where appropriate.

● Develop reusable migration components, automation, playbooks, and reference architectures.

Required experience

● 6+ years of professional software-engineering experience.

● At least 2 years in a customer-facing technical role such as consulting, professional services, solutions architecture, or forward-deployed engineering.

● Expert-level TypeScript and strong React engineering experience.

● Deep, recent, production-level Next.js experience.

● Proven ownership of at least one substantial legacy-application or large-codebase migration.

● Strong understanding of incremental modernization rather than only “big-bang” rewrites.

● Working knowledge of Ruby/Rails applications, APIs, and integration patterns.

● Strong AWS and cloud architecture knowledge.

● Production experience with CI/CD, automated testing, observability, security, performance optimization, and release management.

● Experience building or integrating production AI applications, agents, agent frameworks, or MCP-based tools.

● Ability to communicate with developers, architects, product leaders, and executives.

● Ability and willingness to code, debug, deploy, document, and resolve production issues personally.

● Authorized to work in the United States and able to travel occasionally to customer locations.

Strongly preferred

● Direct production experience deploying applications on Vercel.

● Ruby/Rails-to-Next.js modernization experience.

● Migration from Pages Router to App Router.

● Vercel AI SDK, AI Gateway, eve, Fluid Compute, Workflows, Sandbox, and Observability.

● Experience with high-volume retail, e-commerce, media, healthcare, or financial-services applications.

● Enterprise security, compliance, identity, and multi-region deployment experience.

● AI-assisted migration or code-transformation automation experience.

Candidates who will not fit

● Front-end developers whose experience is primarily UI implementation.

● Managers who are no longer hands-on with architecture and code.

● Engineers with only greenfield Next.js experience.

● Candidates who cannot explain their personal contribution to a production migration.

● Generic cloud engineers without deep React, TypeScript, and Next.js expertise.

● Candidates with AI terminology on their résumé but no production agent or AI application.

● Consultants who require fully specified tasks and cannot operate through ambiguity.

Evidence required from candidates

Candidates must be prepared to present:

1. One legacy-modernization case study, including the original architecture, target architecture, migration stages, risks, and their personal contribution.

2. One production Next.js application or migration they personally designed and delivered.

3. One CI/CD, deployment, or production incident they personally resolved.

4. One production AI-agent, AI application, or agent-framework example.

5. Measurable results such as migration time, deployment-frequency improvement, performance gain, reduced infrastructure cost, or Core Web Vitals improvement.

Technical evaluation

Candidates will receive a simplified Ruby/AWS monolith and be asked to:

1. Assess the current state and identify critical unknowns.

2. Design an incremental migration to Next.js and Vercel.

3. Explain service boundaries, API integration, coexistence, data handling, cutover, and rollback.

4. Design the CI/CD and deployment process.

5. Build and deploy a representative Next.js component.

6. Explain security, observability, performance, testing, and business-continuity decisions.

7. Identify an appropriate AI-agent or AI Gateway use case without forcing AI where it adds no value.

Regards

Mohamed

mohamed@sophusinfo.com