Ingénieur Logiciel Senior, Backend (Node.js, TypeScript, Rust)

Join a high-scale consumer platform team as a Senior Backend Engineer, building the services behind digital experiences used by millions of people every day.

1. Overview

We're partnering with a large enterprise technology organization to place a Senior Software Engineer on a platform team that powers its core customer-facing experiences across web and mobile. The team works across Engineering, UX, Product, Business, and Analytics to ship fast, iterate through continuous experimentation and customer feedback, and integrate advanced capabilities such as Generative AI into production services. We're seeking senior backend engineers with hands-on Node.js, TypeScript, and Rust experience and a deep understanding of how the web works at scale. This is a full-time commitment of 40 hours per week.

This is a W-2 employment position with Cincinnatus LLC, with the opportunity to be placed within a leading enterprise client's engineering organization as part of their extended workforce.

2. Key Responsibilities

• Lead delivery of scoped features through collaborative engineering teams, keeping work aligned with platform and system objectives.

• Design, develop, test, and maintain high-quality, efficient services in Node.js, TypeScript, and Rust, across the full software lifecycle and CI/CD.

• Build and optimize server-to-server integrations and API layers (REST and GraphQL) that serve high-traffic, customer-facing applications.

• Integrate AI/ML capabilities into product services and use generative AI tools to improve engineering productivity.

• Contribute to solution design, conduct code reviews, and apply best practices for scalable, secure, and maintainable systems.

• Monitor application performance, support defect resolution, and drive continuous improvement.

• Mentor peers and contribute to knowledge sharing and engineering excellence across the team.

3. Core Qualifications

• 4+ years of professional software engineering experience (or a Bachelor's degree in Computer Science or a related field and 3+ years), building production systems at a recognized, high-scale organization.

• Hands-on production coding experience in Node.js and TypeScript on the backend.

• Hands-on coding experience in Rust, in production services, performance-critical modules, or substantial systems work.

• Strong web fundamentals: HTTP semantics, cookies, headers, caching, sessions, and server-to-server communication patterns (auth between services, timeouts, retries).

• Experience building or operating high-traffic, consumer-facing web platforms.

• Experience with GraphQL on Node.js (schema design, resolvers, federation) is a plus.

• Familiarity with web accessibility standards is a plus.

• Demonstrable career progression to senior-level ownership.

• Ability to engage reliably for at least 40 hours/week during weekdays.

• Excellent written and verbal communication skills, and the ability to explain complex technical concepts clearly to broad audiences.

About Cincinnatus LLC: Cincinnatus LLC is an enterprise staffing company that partners with leading technology companies to source and employ highly skilled professionals for contingent and contract-based opportunities. Cincinnatus serves as the employer of record for these engagements, providing W-2 employment, payroll, benefits, and compliance, while placing employees directly within client teams to work on high-impact initiatives.

Equal Employment Opportunity: Cincinnatus is proud to be an Equal Employment Opportunity employer. We do not discriminate based upon race, religion, color, national origin, sex (including pregnancy, childbirth, reproductive health decisions, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, genetic information, political views or activity, or any other legally protected characteristic.