Senior Backend JavaScript Developer

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Backend JavaScript Developer based in United States.

You will join a high-performing engineering team responsible for building and operating critical backend services that support large-scale networking infrastructure.
The role focuses on designing and delivering high-performance, secure, and highly reliable distributed systems.
You will work on complex challenges involving network traffic, protocols, latency, and system scalability.
This position offers full ownership of services from design through production and ongoing optimization.
You will collaborate closely with experienced engineers to solve deep technical problems in networking and backend architecture.
The environment is fast-paced, technically demanding, and centered on engineering excellence and continuous improvement.
It is an opportunity to make a direct impact on systems operating at significant scale and complexity.

• Lead end-to-end development of backend features, from system design and implementation to deployment and continuous improvement in production environments.
• Build, maintain, and optimize high-scale backend services with a strong focus on performance, reliability, scalability, and security.
• Contribute to system architecture decisions, ensuring solutions are robust, maintainable, and aligned with long-term technical strategy.
• Work on advanced networking challenges such as traffic routing, proxy behavior, request/response lifecycle, and protocol edge cases.
• Diagnose and resolve complex production issues using debugging and packet inspection tools (e.g., Wireshark and similar technologies).
• Collaborate with cross-functional engineers and stakeholders while actively participating in code reviews and engineering best practices.

Requirements:

• 5+ years of software engineering experience, including at least 2+ years specializing in backend JavaScript / Node.js development.
• Strong understanding of the Node.js runtime and event loop, including performance trade-offs (I/O vs CPU-bound workloads, async patterns, memory management, and blocking risks).
• Proven experience designing, building, and operating production-grade backend systems.
• Solid knowledge of networking fundamentals and protocols including TCP/IP, UDP, DNS, HTTP (1/2/3), TLS, and WebSockets.
• Experience working with MongoDB, Redis, and distributed caching or data storage systems.
• Familiarity with Kubernetes and containerized deployment environments.
• Strong system design skills covering APIs, scalability, reliability, fault tolerance, and performance optimization.
• Comfortable working independently in a fast-paced environment while collaborating effectively within a team.
• Strong English communication skills, both written and verbal.

Nice to have:

• Experience with AWS and SaaS-based architectures.
• Background in debugging production networking issues such as latency, packet loss, and TLS handshake failures.
• Experience with observability tools (logging, metrics, tracing) and incident response/on-call practices.

Benefits:

• Competitive salary aligned with senior-level expertise and market benchmarks.
• Flexible working arrangements, including remote options depending on team setup.
• Health and wellness benefits package (medical, dental, and vision where applicable).
• Opportunity to work on large-scale, high-impact backend and networking systems.
• Continuous learning environment with exposure to advanced distributed systems challenges.
• Collaborative engineering culture focused on innovation, ownership, and technical excellence.