Senior Full Stack Engineer (MERN) - Codup

ABOUT THE ROLE

We are looking for a Senior Full Stack Engineer to join an active mobile product delivery engagement. This role sits at the core of the backend architecture, owning the middleware layer that connects a mobile commerce platform to multiple integrated services, including a commerce engine, a search platform, and an async messaging infrastructure.

In addition to the backend, this developer will build and own a web-based admin dashboard used by the client's marketing team for day-to-day content and campaign management. The right candidate is comfortable working across the full backend and web stack, takes ownership of complex integration challenges, and writes production-grade code that holds up under real load.

This role works closely with a Tech Lead who provides architectural direction and handles high-level design decisions. The Senior Full Stack Engineer is expected to execute within that architecture independently and flag blockers early.

REQUIRED EXPERIENCE

5 or more years in full-stack development with at least 4 years of production Node.js experience. The candidate must have worked on at least one project involving multiple integrated third-party platforms with complex data flow requirements.

MUST-HAVE SKILLS

The following are non-negotiable. Every point will be assessed during the evaluation process.

• Node.js API Development- Building production-grade REST APIs including authentication, request routing, error handling, and rate limit management under high traffic conditions.
• PostgreSQL- Schema design, query optimization, and implementing queue and retry state patterns in a production environment.
• Shopify API Integration- Hands-on experience with the Shopify Admin API, including webhooks, catalogue sync, and order management.
• Elasticsearch- Index design, indexing pipelines from an external data source, search relevance tuning, and Arabic analyzer configuration.
• Next.js- Building functional, workflow-driven web admin applications consuming REST APIs, including role-based access and form-heavy interfaces.
• Async Messaging and Queue Systems- Hands-on experience with SQS, SNS, or similar message queue systems for decoupled async processing pipelines.
• Retry and Reconciliation Logic- Designing and implementing durable retry queues and failed sync recovery mechanisms in a multi-platform integration context.
• Third-Party Service Integration- Experience integrating external services such as Firebase, OneSignal, or similar platforms via REST APIs.
• Multi-Platform Integration Awareness- Understanding end-to-end data flows across multiple connected services and the ability to debug issues that span more than one system.
• Performance-Aware Development- Writing code with peak load behavior in mind, including efficient query patterns, caching strategies, and avoiding bottlenecks in high-throughput scenarios.
• AI-Assisted Development- Comfortable using AI coding tools and agents to accelerate output, with the discipline to critically review and take ownership of everything committed to the codebase.

GOOD TO HAVE

The following are not required but will strengthen a candidate's profile for this engagement.

• Prior experience building a commerce or marketplace platform at scale.
• Familiarity with Shopify's webhook reliability patterns and API versioning.
• Experience with Arabic language search tuning beyond basic analyzer setup.
• Working knowledge of AWS services relevant to backend infrastructure, including ECS, SQS, and RDS.
• Exposure to data privacy regulations in the GCC/MENA region, specifically PDPL.
• Experience building admin dashboards or internal tools for non-technical end users.